The Mariana Trench

Misha Glenny and guests discuss one of the wonders of the natural world. In 1875 in the western Pacific, the crew of HMS Challenger discovered the Mariana Trench which turned out to be deeper than Everest is high, by two kilometres. Trenches like Mariana form when one tectonic plate slips under another and heads down and there are around fifty of them globally. While at one time some thought it was too dark and deep for life there and others wildly imagined monsters, the truth has turned out to be much more surprising. With Heather Stewart, Director of Kelpie Geoscience and Associate Professor at the University of Western Australia Jon Copley Professor of Ocean Exploration and Science Communication at the University of Southampton And Alan Jamieson Director of the Deep Sea Research Centre at the University of Western Australia Producer: Simon Tillotson Reading list: Susan Casey, The Underworld: Journeys to the Depths of the Ocean (Doubleday, 2023) Jon Copley, Deep Sea: 10 Things You Should Know (Orion Books, 2023) Hali Felt, Soundings: The Story of the Remarkable Woman Who Mapped the Ocean Floor (Henry Holt & Co, 2012) M. E. Gerringer, ‘Pseudoliparis swirei: A newly-discovered hadal liparid (Scorpaeniformes: Liparidae) from the Mariana Trench’ (Zootaxa 4358 (1), 161-177, 2017) A. J. Jamieson, The Hadal Zone: Life in the Deepest Oceans (Cambridge University Press, 2015) A. J. Jamieson et al., ‘A global assessment of fishes at lower abyssal and upper hadal depths (5000 to 8000 m)’ (Deep-Sea Research Part 1. 178: 103642, 2021) A. J. Jamieson et al., ‘Fear and loathing of the deep ocean: Why don’t people care about the deep sea?’ (ICES Journal of Marine Science. 78: 797-809, 2020) A. J. Jamieson et al., ‘Microplastic and synthetic fibers ingested by deep-sea amphipods in six of the deepest marine environments on Earth’ (Royal Society Open Science, 6, 180667, 2019) A. J. Jamieson et al., ‘Bioaccumulation of persistent organic pollutants in the deepest ocean fauna’ (Nature Ecology and Evolution. 1, 0051, 2017) V. L. Vescovo et al., ‘Safety and conservation at the deepest place on Earth: A call for prohibiting the deliberate discarding of nondegradable umbilicals from deep-sea exploration vehicles’ (Marine Policy. 128, 104463, 2021) J. N. J. Weston et al., ‘New species of Eurythenes from hadal depths of the Mariana Trench, Pacific Ocean (Crustacea: Amphipoda)’ (Zootaxa. 4748(1): 163-181, 2020) In Our Time is a BBC Studios Production Spanning history, religion, culture, science and philosophy, In Our Time from BBC Radio 4 is essential listening for the intellectually curious. In each episode, host Misha Glenny and expert guests explore the characters, events and discoveries that have shaped our world.

• 0:00Speaker 00

  This BBC podcast is supported by ads outside the UK.

• 0:05Speaker 00

  Sometimes we all need an extra helping hand, especially with a tricky business problem you've been putting off. Claude is the AI for just that. It's the collaborator that understands your entire workflow and thinks with you, not for you. And Claude isn't just for quick questions. Hand it a whole task, like turning a folder of scattered notes into a report, and it does the work and hands back something finished that you can open and edit. Claude can now draft a doc or deck right in front of you, and Claude Design now lives right inside Claude. Describe the website or prototype you're picturing, attach your design system, and it comes back in your own design language, ready to edit right on the canvas. It works with your files and the tools you already use,

• 0:49Speaker 00

  like Gmail and Slack. And whether you're debugging code at midnight, building a financial model, or strategizing your next business move, Claude extends your thinking to tackle the problems that matter. For problems worth solving, get started with Claude at claude.ai/solve. That's claude.ai/solve. And check out Claude Pro, which includes access to all of the features mentioned in today's episode. claude.ai/solve.

• 1:16Speaker 01

  Hey, I'm Niall Rogers. This fall, I'll be driving across the country, meeting some of today's coolest and most fascinating artists. We'll explore the stories before the moments that changed everything. Because every musician remembers the moment where it all began. Experience Before the Moment, a Lincoln original series on the iHeart Radio app, YouTube, or wherever you get your podcasts.

• 1:48Speaker 02

  OnDeck is built to back small businesses like yours. Whether you're buying equipment, expanding your team, or bridging cash flow gaps, OnDeck's loans up to $400,000 make it happen fast. Rated A+ by the Better Business Bureau and earning thousands of five-star TrustPilot reviews, OnDeck delivers funding you can count on. Apply in minutes at ondeck.com. Depending on certain loan attributes, your business loan may be issued by OnDeck or Celtic Bank. OnDeck does not lend in North Dakota. All loans and amounts subject to lender approval.

• 2:18Speaker 03

  This is In Our Time from BBC Radio 4, and this is one of more than a thousand episodes you can find in the In Our Time archive. A reading list for this edition can be found in the episode description wherever you're listening. I hope you enjoy the programme. Hello. In 1875, in the Western Pacific, the crew of HMS Challenger discovered the Mariana Trench, which turned out to be deeper than Everest is high by some two kilometres. Now trenches like Mariana form when one tectonic plate slips under another and heads downwards

• 2:57Speaker 03

  towards the Earth's mantle, and there are around 50 of them globally. Now, some people used to think that it was too dark and deep for life to exist there. Others imagined monsters lurking at the bottom of the ocean. The truth has proved to be more intriguing than either of those. With me to discuss the Mariana Trench are three people who were all veterans of this kind of environment. Alan Jamieson, Director of the Deep Sea Research Centre at the University of Western Australia, John Copley, Professor of Ocean Exploration and Science Communication at the University of Southampton, and Heather Stewart, Director

• 3:40Speaker 03

  of Kelpie Geoscience and Associate Professor at the University of Western Australia. Heather, I'd like to come to you first. Can you just describe the Mariana Trench to us? How big is it? Where is it? And if we could see it, what would it look like?

• 3:59Speaker 04

  Yeah, fantastic. The Mariana Trench is what's called a subduction trench, and what it looks like is this long, curved, deep within the Western Pacific, and that's formed, as you introduced, through a process of plate tectonics. So we have denser oceanic lithosphere, so the Pacific Plate. That plate encompasses the entire Pacific Ocean, and that is being thrust and pulled underneath the Joining continental plates. So this process of plate tectonics by which these oceanic plates are getting taken down into the mantle and recycled, that downward flexure causes these ultra-deep parts of our world, most famously the Mariana Trench and the

• 4:44Speaker 04

  other trenches that surround the Pacific, the so-called Pacific Ring of Fire. And that's how these ultra-deep places are formed. And the maximum depth of the Mariana Trench is 10,925 metres, and that's about 98 times the height of St Paul's Cathedral, which is just, it's a really hard number to sort of visualise in your head when you start to think about these sort of deep water environments.

• 5:10Speaker 03

  And how long is it exactly?

• 5:12Speaker 04

  It's about 2,550 kilometres long and it sort of arcs around the Mariana Isles in the Western Pacific there.

• 5:22Speaker 03

  Now, you're all experienced divers in these terrains. Heather, what's it like to go down a trench?

• 5:30Speaker 04

  It's absolutely incredible. I mean, all three of us around the table here have been in submersibles, but from my personal point of view, there's the moment when you're sitting on the sea surface and you get the clear to dive call. And that colour change as you start to fall through the water column and the change from the sort of clear waters on the sea surface through the brightest shades of blue down to absolute pitch blackness. But then, of course, all of that, you're sitting in silence. And that is so humbling as well as very, very exciting. Because of course, after a few hours, you start to come to the seafloor in these sort of deep subduction trenches. And I've been lucky enough to dive to the bottom of the Tonga Trench. But that moment when you turn on

• 6:14Speaker 04

  the lights of the submersible and you start to see the seafloor coming up underneath you is absolutely fantastic. And as a geologist, knowing That you're the first person to set eyes on this seascape, if you will, but also starting to look and your brain is already starting to process what you're seeing out of the viewports and trying to put that into some sort of geological context, you know, are we landing on sort of soft sediment seafloor or are we coming down on rocks? What type of rocks are there? Are there any structure in those rocks? Are we seeing faults? You know, what life is encrusting and are being associated with that habitat down there? So you're constantly taking this information in and trying to form a sort of hypothesis

• 6:55Speaker 04

  and that you're testing during the submersible dive itself. But I mean, it's absolutely, you know, the very first dive I did, the pilot sort of joked that, you know, you had to turn up the oxygen because I was getting very excited. So I was using up more oxygen in the environment inside the sub. But it's, it's truly, you know, the being there and sort of seeing it yourself is something that can't be replicated through other means.

• 7:18Speaker 03

  Fascinating. And Alan, I believe that you have gone amongst our guests the furthest down the Mariana Trench. Can you tell us about that experience?

• 7:30Speaker 05

  Yeah, it was a good few years ago now, but it was a, it was a mistake.

• 7:36Speaker 03

  How can you, how can you go down the Mariana Trench by mistake?

• 7:40Speaker 04

  Woke up one morning.

• 7:42Speaker 05

  It wasn't planned. We went there to do, I think it was four or five dives on the deepest place on earth. And it was like, I think the first one was the third time it's ever been done. And no one thought we'd ever do it. They figured that we'd probably get one in, maybe two before the sub breaks. So we run out of time or there's weather or whatever. And for some reason, we just did one every two days for a week and we got all, we ticked all the boxes because some of the dives are to do with the classification of the sub. Some of them because of the owner wants to do it at the time. Other ones were to do with the manufacturer. And we did four and nobody, nobody expected us to do that. And so. Interesting, the guy called Don Walsh, he was the guy who did the first dive ever in nineteen sixty. He was with us and he came in one day and said, uh, there's another one. It's just time for another one. Do you wanna do it? I was like, yeah, sure, yeah. And he said, well, where do you wanna dive?

• 8:27Speaker 05

  And I said, well, I don't really wanna dive Challenger deep because it's, we've just done it four times and there's actually nothing much there. Uh, but it's just on a little bit.

• 8:33Speaker 03

  That's the deepest bit of the Mariana Trench.

• 8:36Speaker 05

  Yeah, yeah, we've done it twenty-two times now, so I was right, there isn't much there. But, uh, I said, I wanna go next door. There's a place next door called Serenity, which is like ten thousand seven hundred and there was reasons to believe it would be a slightly more interesting. So, yeah, and before or not, next morning we were down at ten thousand seven hundred and something meters and we found these big sulfur mounds and all sorts of interesting stuff. It was brilliant. So it wasn't, it wasn't planned, it wasn't really supposed to happen.

• 8:58Speaker 03

  What are the challenges for the submersibles themselves? I mean, because they must be operating under immense pressure and yet they've got to sustain an environment in which humans can live. Uh, or exist for four or five hours or whatever.

• 9:13Speaker 05

  Yeah, there's two parts to it. So we've gone down to environments which are, pressure-wise, are about one ton per square centimeter, if not a bit more. So the engineering for that is actually relatively easy because it's linear. So you just make things thicker and thicker. We use titanium inside the sphere. And we use all sorts of materials that can get us back to the surface and so on. But the other problem we have is not just the pressure at depth, it's actually the distance from the surface. So communication with the surface is very difficult. For all sorts of safety reasons, we have protocols in place where we have to contact the surface every fifteen minutes. Every half hour has to be a voice one, so we have an underwater telephone where we can talk to the surface. That's the biggest problem, is trying to punch an acoustic signal through seven miles of water and then trying to listen for them coming back.

• 9:52Speaker 05

  And we've kinda nailed it now, but some of the other problems we have is tracking is quite often, well, up until recently, there hasn't been any products on the market that we can use to track where the sub is. So for the last five, six, seven years, we've been doing, we've no tracking at all. So we've got very rudimentary tracking, but not like you would in shallow water. So there's a certain degree of challenges to do with just being very, very far away from the ship as well as the pressure at bottom.

• 10:16Speaker 03

  How does the sound travel back and forth between the ship and the submersible?

• 10:21Speaker 05

  We have a thing called an underwater modem, and it's an old Australian military device that we push a button and say hello, and then you release the button and it scrambles into an acoustic signal, goes up. And you can kind of tell, it's weird, it scrambles into acoustic signal, but you can tell who's talking. It's really bizarre. You can almost hear the accent in it. And then they hear it, and then they talk back. And you have a lot, we've got text messaging now as well, which is quite nice.

• 10:44Speaker 03

  John, these depths are often called Hadal zones. What does that, what does that mean? What is a Hadal zone?

• 10:49Speaker 06

  It's from the Greek for Hades. So the idea is this is the greatest depths of the ocean. So this is, there are these popular schemes for dividing the ocean up into different depth zones and giving them names. But environmentally, ecologically, most of them don't make sense. The Hadal zone is one that in a way does make sense if we just say, well, that's ocean trenches. Ocean trenches tend to start at about 6,000 metres. But that said, there are some environments in the deep ocean that aren't ocean trench, which are at more than 6,000 metres, which is where these zones kind of break down. But in a way, you can think of it as a shorthand for being ocean trenches.

• 11:28Speaker 03

  Right. That's nice and simple. How was it discovered? The Mariana Trench in particular?

• 11:33Speaker 06

  So you mentioned in your introduction HMS Challenger. So this is a global voyage of discovery in the early 1870s. And it has two main goals. One is scientific, to map the ocean floor, understand its undulations and the extent of life in the deep ocean, and also a strategic goal as well. And that's to scout the routes for submarine telegraph cables, which are such a huge technological revolution of that time. I mean, I think right up there with the invention of the printing press and the impact they had on the world.

• 12:02Speaker 03

  So we had telegraph cables across the Atlantic in the 1860s. The Pacific was even more challenging.

• 12:09Speaker 06

  Exactly. And people wanted to wire up the British Empire. So one of the goals of HMS Challenger, and the reason it got funded, was this strategic Strategic goal. Anyway, twenty third of March, eighteen seventy five, HMS Challenger has been, it's in the Pacific and it has been pushed off course by baffling winds as they record in their log. And they decide to make a depth measurement where they've ended up. So they lower a weighted line and they record a depth of four thousand four hundred and seventy five fathoms, which is eight thousand one hundred and eighty four metres, I think. So that was the deepest place that they measured on their voyage. It's not actually the deepest point in the ocean and it's

• 12:52Speaker 06

  not even the deepest place that had been measured at that time. So where they made that measurement, they were actually about twenty five kilometres from what we now recognise as the deepest part of the Mariana Trench, the Challenger Deep, and about two thousand seven hundred metres short of that. And it wasn't then thought to be the deepest part of the world's oceans, because a year earlier, a ship called the USS Tusk Aurora, which was also scouting submarine telegraph cable routes in the Pacific for the United States, had measured eight thousand five hundred and thirteen metres for much further north in the Pacific in what we now recognise as the Kiral Kamchatka Trench. So HMS Challenger found this deep depression, literally by accident, near the Mariana Islands, and there were no other depth measurements in that area for another

• 13:36Speaker 06

  twenty four years. So they found a deep spot. They didn't know it was part of a trench. It wasn't called the Mariana Trench at all at that time, and it wasn't even the deepest known point at that time. So if we jump forward a little bit, eighteen ninety four, HMS Penguin measures nine, just over nine thousand one hundred metres in the South West Pacific in what we now recognise as the Kermelek Trench, so that then becomes the deepest known place on Earth. But not for very long, eighteen ninety nine, a ship called USS Nero. Again, scouting submarine cable routes near the Philippines measures 9,636 metres. That becomes the deepest known place on earth, what we now recognise as the Philippine Trench.

• 14:17Speaker 06

  And that stayed as what people thought was the deepest place on earth until 1951. And these were individual depth measurements, and people didn't realise they were part of these trenches and these features that Heather's described. That came also, though, at the end of the 19th century. So there was a map published of the depths of the world's oceans by a cartographer called Alexander Supan. And he showed that some of these places where there've been these big depth measurements were trench-like features, not actually the Mariana one on his map, but he identified the Aleutian Trench. And he also proposed that these things should be named after the geographic features that they're near to, so that people don't get confused.

• 14:58Speaker 03

  So that's why Mariana, turns out to be Mariana, because it's near the Mariana Islands?

• 15:03Speaker 06

  Indeed, and Challenger Deep, which is what it was called before on an earlier map in 1877, that becomes eventually the deepest known bit of the Mariana Trench.

• 15:14Speaker 03

  Heather, what do we see when we get down to the bottom of the trench, on the beds of the trenches, in geological terms? Is this like a sort of conveyor belt of rock?

• 15:26Speaker 04

  Yes, indeed, and in that sort of really large-scale, big geological processes frame, then we're looking at a conveyor belt of oceanic plate coming into the trench, being bent and thrust down underneath that overriding plate. So that's where we get that conveyor belt. But in terms of when we're actually looking at the seascape, you know, it can vary quite a lot. So we have what are called hemipelagic and clay-rich sediments that drape that seascape, that topography of rock. But once we're actually in the trench, you know, we don't only have that oceanic plate, which are composed of volcanic rocks like basalts and things. We actually have, you know, the forark, so all these rocks and sediments are also getting scraped off

• 16:11Speaker 04

  onto the overriding plate as it's being subducted in. So we get this melange of sediment. And rocks, but we can also see bits of exposed mantle in these trench environments as well. So these are sort of gabros.

• 16:25Speaker 03

  What does mantle look like?

• 16:26Speaker 04

  It's actually really cool and we've got some amazing footage of that and it's these massive dark rocks, but they've got really big major faults and joints in them. So I mean, it's very characteristic and it's got a lovely sheen to them as well. So in terms of what you're looking at out of the viewports and what you're looking back on the on the video that's recorded, it's a very striking environment. But what's also really cool is that when the process of subduction is happening, it almost starts this catalyst of other things that are happening. So we see mud volcanoes and we see vent systems, you know, there's a the Shinkai Vent System is on that forearc of the Mariana Trench and it's not like what we might think in terms

• 17:09Speaker 04

  of black smokers and, you know, those amazing documentaries that we see where you've got the sort of pump of of black material kind of coming out of the the seafloor and those very dark brown big edifices and stuff. These vent systems in the Mariana, the Shinkai Vent System, for example, are made out of carbonates, so they're white pristine white chimneys that are preserved on the seafloor. And the fluids that are erupting from these systems are being sampled and tested for the chemistry. So we're looking at what minerals are being dissolved by the water that is being taken down by this process of subduction and is percolating through the rock mass. And it's dissolving out all of these minerals and then it's reprecipitating them.

• 17:53Speaker 04

  And that's when Alan was talking about the sulfur mounds in the in the Serena Deep, you know, the sort of bright yellows, I mean, the colors that you can see on the seafloor can take your breath away. Some of the other footage that we have from the Java Trench, for example, I mean, Alan, we've got yellows and blues and and all of these chemosynthetic bacteria that are living off the mineral content coming out of these vents and the the cracks and fissures on the seafloor.

• 18:18Speaker 03

  And just explain to us quickly what turbidity currents are.

• 18:23Speaker 04

  So turbidity currents, they're, you might like to think about them as underwater waterfalls, where we've had something, whether it's through gravity, so it's just, you know, you've got a slope that is being loaded with sediment, much like whenever you're driving through the Highlands and you look, especially after a heavy rainfall, you might see the sides of the glen that you're driving through, you know, you can see the material is sort of slipping down slope. So we can get the same comparable processes underwater in these trench systems as well. But then, of course, we've got the more dramatic, perhaps the more well-known events that are triggered by earthquakes or volcanic eruptions, for example. But basically, these trigger movement of vast quantities of material down slope,

• 19:06Speaker 04

  huge speeds as well. And it is a really great mechanism for transporting not just sediment from higher slopes down into these trench basins, but also it's transporting food and nutrients for the communities that live down there.

• 19:22Speaker 03

  Well, let's go on to those communities. And Alan, let me ask you, what kinds of life are we seeing at these depths?

• 19:30Speaker 05

  There's all sorts. So there's, you can kind of categorise all deep sea animals into two different categories. There's those that go down to about 8,000 and there's those that go beyond that. So when you look at things like fish, prawns, urchins, brittle stars, sea stars, squid, octopus, you find all them deeper than 6,000 metres, but they rarely ever go beyond eight. So it's obviously there's a barrier there, which is quite difficult. If the species has adapted to high pressure and go beyond that, they go all the way and they don't seem to care about pressure at all. So there you've got things like little tiny hoppers called amphipods. There are things called isopods and polychaete, which are pillbugs and scale worms. And there's normal looking jellyfish, there's anemones down there. But once this seems, once an animal seems to have evolved to break the 8,000 metre barrier,

• 20:15Speaker 05

  it almost adopts this complete resilience to pressure. And sometimes their depth range can be 5,000 metres, which is incredible. So at the very, very bottom, there's one animal which I think has become kind of really important to us because we're finding it at the bottom of every single deep trench we go to. And you have to be deeper than about eight and a half to 9,000 metres to see it. And it's just an anemone. It's called a Galatea entimon. And they live in a little tube and they look like a little white flower. Really quite beautiful looking thing, but we can't find them anywhere else except at the very deepest points of the really deepest trenches. So there's that. Everything else tends to be quite small at the deepest points, but when you, as I say, when you get to eight thousand, there's quite a lot of large animals still kicking around, which is people find quite surprising. And they don't look weird. They look, if anything, kind of goofy.

• 21:00Speaker 03

  And you, I, I believe you discovered or named one called the snailfish.

• 21:05Speaker 05

  Oh, the snailfish is a known family. We discovered the Mariana snailfish. We discovered heaps of fish. We just don't name them anymore because it's too difficult. But yeah, we find snailfish all the time. So we named the Mariana one because it was quite prestigious. So for quite a few years, it was the deepest fish in the world. Unfortunately, it's not anymore. There's one further north of Japan, which is slightly deeper, but they're all kind of the same. They all look goofy and weird and they're sort of flaccid looking little things. But they are the deepest in the world. And weirdly, the, the family of fish of snailfish are not actually deep sea fish. They're shallow water fish. They're just, they've completely taken over. So there's 300 species. You find them up estuaries and stuff and snailfish are now a thousand meters deeper than actual proper, well, I consider proper deep sea fish.

• 21:45Speaker 00

  Sometimes we all need an extra helping hand, especially with a tricky business problem you've been putting off. Claude is the AI for just that. It's the collaborator that understands your entire workflow and thinks with you, not for you. And Claude isn't just for quick questions. Hand it a whole task, like turning a folder of scattered notes into a report, and it does the work and hands back something finished that you can open and edit. Claude can now draft a doc or deck right in front of you, and Claude design now lives right inside Claude. Describe the website or prototype you're picturing, attach your design system, and it comes back in your own design language, ready to edit right on the canvas. It works with your files and the tools you already use, like Gmail and

• 22:29Speaker 00

  Slack. And whether you're debugging code at midnight, building a financial model, or strategizing your next business move, Claude extends your thinking to tackle the problems that matter. For problems worth solving, get started with Claude at claude.ai/solve. That's claude.ai/solve. And check out Claude Pro, which includes access to all of the features mentioned in today's episode. claude.ai/solve.

• 22:56Speaker 01

  Hey, it's Niall Rogers, host of Before the Moment, a Lincoln original series. I'm driving across the country, meeting some of today's most fascinating artists. We're exploring the stories before the moment that changed everything. This week, I'm joined by rising star Sienna Spiro.

• 23:15Speaker 07

  My first ever in-the-world show was when I was 10, and I sang at a pub called The Georgian Devonshire. I was so nervous. I was 10, so they let me in only to sing my song, and then they kicked me out right after. And then I remember I wrote, I've been writing since I was 10, so I wrote this song called "Lady in the Mirror," made this little track with it. But I just like pressed it, and I remember I sang this song, and there was like five people in there. And I remember how myself I felt, and I felt like I understood myself and understood what I needed to do.

• 23:42Speaker 01

  So does that take us back to, "I sing just to know I'm alive"?

• 23:46Speaker 07

  Hundred percent, hundred percent, my whole life.

• 23:49Speaker 01

  Experience Before the Moment, a Lincoln original series on the iHeartRadio app, YouTube, or wherever you get your podcasts.

• 23:58Speaker 02

  OnDeck is built to back small businesses like yours. Whether you're buying equipment, expanding your team, or bridging cash flow gaps, OnDeck's loans up to $400,000 make it happen fast. Rated A+ by the Better Business Bureau and earning thousands of five-star TrustPilot reviews, OnDeck delivers funding you can count on. Apply in minutes at ondeck.com. Depending on certain loan attributes, your business loan may be issued by OnDeck or Celtic Bank. OnDeck does not lend in North Dakota. All loans and amounts subject to lender approval.

• 24:25Speaker 03

  John, how do these animals and the anemones and so on, how do they withstand pressure at 10,000 meters below it? How does it happen?

• 24:37Speaker 06

  Well, the challenge of pressure for animals in the deep sea is really often not what we perhaps imagine it is. So, I mean, to illustrate that, I was, the last expedition I was on in the Arctic, we took an ordinary, uncooked chicken egg. And we sent it down to three and a half thousand metres on the outside of one of our deep diving vehicles. That's about the average depth of the world's ocean. And it came back without a crack on it. And that's not because it's somehow stronger than our submersibles. You know, we then cracked it open in the in the galley to show that it was it was it was an ordinary egg. That's because, think about that chicken egg. What's it made of? It's made of solid matter for its shell, and it's filled with liquid. And those are pretty much incompressible forms of matter. You know, if you imagine dropping a stone into

• 25:21Speaker 06

  the Mariana Trench, it sinks down into the ocean. It doesn't at some point suddenly implode because there's no gas-filled space inside it for it to get squashed down into by the pressure. Similarly, with liquids, if you get a syringe of water, you know, stick your thumb over the end, try and push down that plunger, you won't budge it compared to a syringe of air, the same kind of thing. So for deep sea animals, whose bodies are made of solid matter in their tissues, liquid body fluids, in a sense, they're not mechanically withstanding pressure, a difference in pressure between their insides and their outsides, in the same way that our deep diving vehicles do. Our vehicles have to maintain, you know, a gas-filled space inside them at normal atmospheric pressure, either to keep us alive as occupants, or to keep electronics dry if it's an uncrewed vehicle. But it's not

• 26:04Speaker 06

  like that for deep sea life. There is a challenge, but it's it's about what happens with molecules in cells. But it's not about mechanically withstanding pressure.

• 26:13Speaker 03

  Can you just go into that a bit about the molecules in the in the cells? Because they act in a rather different way than than the molecules in our cells do.

• 26:23Speaker 06

  So some of the problems with pressure, for example, involve protein molecules folding up into the right three-dimensional shape that they need to be to work as enzymes. And, you know, we need the enzymes and they're carrying out all the living processes in cells. And that's a big problem because high pressure traps water molecules on the unfolded protein as it's been kind of put together inside the cell, and prevent it from folding up into the right shape to do its job. So that's one challenge of pressure. And so a lot of deep sea animals have these small molecules that we call chaperones, that help to pull the water molecules off the unfolded proteins, so they fold up into the right shape. Sometimes the animals have a different kind of protein structure. Their protein is made of a different sequence of these little like bead like amino acids,

• 27:08Speaker 06

  which again helps them form the right structure under pressure. And it's also the cell membranes, the things that enclose the cells. Now, that's normally a very fluid bilayer of lipid molecules, fat like molecules. Under high pressure, that can become very rigid and that can stop, you know, messages getting in and out of the cell and so on. So again, a lot of deep sea animals have different composition of lipid molecules in their in their membranes to overcome that.

• 27:34Speaker 03

  So a fundamentally different evolutionary path from from say humans.

• 27:39Speaker 06

  Well, adaptations, adaptations to their environment, just tweaks, if you like, as to, you know, nature coming up with a solution to these challenges.

• 27:47Speaker 03

  Heather, back to what we were talking about, you mentioned the landfalls and earthquakes and volcanoes. How stable is that and does that impact on the the animals living at the at the bottom or in the trench?

• 28:03Speaker 04

  In terms of stability, I mean, it is a very dynamic environment, you know, being part of the the ring of fire, the Pacific ring of fire, of course, you know, we've got volcanic eruptions, we've got volcanics going on, we've got the earthquakes and everything. It is quite what we might call a sort of slippy boundary at the at the Mariana. So we don't, we see a lot of earthquakes. I mean, it is an active subducting margin, but it's not stuck. There are other margins that are sort of become stuck and then we've got a huge buildup of geological forces that are trying to sort of unstick that margin. And that's where we get these huge earthquakes that cause such devastation in places. So in terms of the Mariana.

• 28:42Speaker 03

  And those earthquakes did trigger tsunamis and things like that.

• 28:45Speaker 04

  And they can trigger tsunamis, for example, yeah. So as I was saying earlier, in terms of keeping the movement of nutrients and sediments from the shallower four arc down into the trench basin, so that's a constant evolving and occurring process. So there it is constantly changing and we've got some amazing footage from up and around the corner a little bit, the Japan trench, where you can see rock failures and the block failures. So sort of going back to the basics of sort of geotechnical elements. We can see that happening, not just in this rock mass, but also with this semi-consolidated, so the sediments that are a bit stuck together and are starting to behave more like a coherent

• 29:27Speaker 04

  rock than a soft squishy substrate. And we can see those failure planes and mechanisms happening as we traverse in the submersibles and the remotely operated vehicles that we're using.

• 29:39Speaker 03

  Alan, what happens when you go down there? What do you see? Is it a pristine environment?

• 29:44Speaker 05

  No. Sometimes there are places that look very pristine, but I mean, I've probably done about probably over 30 dives now, and I don't necessarily recall any dive that haven't seen something man-made. Probably everyone. Maybe there's one or two that haven't. Some of them are really bad. So I remember doing a 10,000 metre dive on the Philippine trench, which was the spot where the Galatia expedition in the 50s had found a rock that, which was a Galatian, Galatian timon, by the way, the one I was mentioning earlier. So we dove on that spot and we filmed them alive, and that's great. But we also saw something like 19 plastic bags on the same dive, just floating around. You could read the logos off them. There was an eco-friendly plastic bag came past, and you're like, really? How eco-friendly

• 30:28Speaker 05

  is that? And then there are other dives which are more serious. So going back to Mariana Trench, diving the Challenger Deep, the whole western side of Challenger Deep, which is where Don and a guy called Picard dove in 1960, is now a no-go zone because that whole area is just covered in discarded fibre optic cable. And so someone in the last 10, 20 years, maybe it's because something to do with listening to the naval base on Guam, or maybe it's in guys in the military, I don't know, but people have been doing a lot of experiments at the deepest point. And now we have hours and hours of footage of fibre optic cable either just discarded or actually taut and tight across. And if you're in a self-propelled vehicle like a sub, you do not want to be anywhere near fibre optic

• 31:09Speaker 05

  cable. Very, very dangerous. And it's everywhere now. But it's only on Challenger Deep. It's not anywhere else in the Mariana, and it's not seen anywhere else in any other trench. So there are things like that where that's kind of almost deliberate, that someone's been doing something there. But one of the weirdest ones, I think, was last year we were down, I think it was 5,000 metres somewhere. Just on the equator and four days north of Samoa and we were driving along and doing the usual thing. I was telling the pilot, go and have a look at this, go and have a look at that. And we saw this red thing. I thought, that's weird. I wonder what that is. And let's go and have a look and pulled up alongside it. And it was just a packet of Chinese cigarettes, just lying there, thousands of miles away from anywhere, as if someone had just dropped them out of their pocket. And, you know, it's bizarre. It's really quite bizarre.

• 31:49Speaker 04

  It can really throw you as well when you're sort of going like, because you're so focused on trying to, you know, record as much scientific data and information and the commentary that as you're going along on the seafloor.

• 31:59Speaker 05

  And then out of the gloom.

• 32:01Speaker 04

  Well, out of the gloom, you sort of see something, you know, and I think, you know, on the Nova Canton Trough as well, I had a dive at six and a half thousand metres. And I said to the pilot, I was like, oh God, there's, there's something over there. Like, that's going to be, and it was a cardboard box. It's just, you know, you're like, oh, oh, sugar, I've just like deviated from the plan because I thought that was going to be something, you know, geologically or ecologically monumental. And it's like, oh, okay, yeah.

• 32:26Speaker 05

  The Puerto Rico trench was probably bad.

• 32:27Speaker 04

  Oh yeah, that was terrible.

• 32:29Speaker 05

  Had gates and magazines and plates and Coke cans and beer bottles. But I mean, it's sitting in hurricane alleys. I think when these hurricanes, it's not necessarily a story of human folly. I think when you have tsunamis and hurricanes, a lot of material just goes offshore. And if you happen to be next to a trench, it's going to end up there. And it's quite, it's quite depressing to see it.

• 32:46Speaker 03

  Although the point you make about fibre optic cables on Challenger Deep seems to me to be quite, quite interesting.

• 32:54Speaker 05

  The coolest thing about Mariana in terms of manmade naughtiness is there's an S R seventy one Blackbird, you know, the old aircraft from the nineteen sixties, the big black, really cool looking thing. And one of them crashed. They didn't want the Chinese to get it. So they took it out of Guam, out to the Mariana and threw it off the back. You can see pictures of it online. So somewhere in the Mariana, there's a Blackbird, which would be the coolest dive ever.

• 33:16Speaker 04

  I beg to differ, you know.

• 33:18Speaker 05

  They haven't released the coordinates for exactly where it is.

• 33:20Speaker 03

  I bet the Chinese have found it by now.

• 33:23Speaker 04

  Just not telling anyone.

• 33:24Speaker 03

  John, I want to come back to the, to the animals down there. How do they feed? What, what are they feeding on apart from human junk?

• 33:33Speaker 06

  Most of the time, they're feeding on what rains down into the trench. And trenches are interesting because they act a little bit like a funnel. In that there's this stuff that has the poetic name marine snow. But basically, it is poo of all the animals that are living in the ocean. And it is dead bodies of all things living in the ocean. And this marine snow sinks down. It does get concentrated in the trenches through this sort of funnel effect. And so the bottom of your trench, I mean, it's a combination of both a toilet and a mortuary. But that's what things will make a meal of. And they'll make a meal of anything that they can. So oddly enough, some of the animals that live at the bottom of the trenches are able to digest things like wood. Which a lot of animals in the ocean don't bother with.

• 34:18Speaker 06

  It's quite hard to kind of crack the molecules in wood to make a meal of it. But if that sinks and nothing has eaten it on the way down, and that's what you get at the bottom of the trench. Then there's a strong driver for any organism that can make a meal of it. Now, there are some places in trenches, though, that are really exciting. Where there are chemical-fuelled islands of life that break all the rules. So what we call cold seeps. There, as Heather mentioned, where you've got these plates subducting. You get the sediment being scraped and squeezed on the subducting plate. And that squeezes whatever's in that sediment out of it. And so if that's had rotting organic matter in it over, you know, many, many millennia. That's broken down into methane. Methane gets pushed out of the seabed.

• 35:02Speaker 06

  You get these, what we call cold seep communities. And that's where life is incredibly abundant. Now, they haven't been seen yet in terms of animal colonies in cold seeps in the Marianas. But they have been seen in the Kiralkamchakka and the Aleutian trenches. More than 9,000 metres deep, which are the deepest-known islands of this chemically-powered life. Which we have on earth, which are hugely exciting.

• 35:25Speaker 03

  Alan, from a scientific perspective, Mariana must be an achievement to go down there. But is it the most interesting scientifically? Or is it just the feather in your cap of having been deeper than anywhere else?

• 35:40Speaker 05

  It's a bit of both. It's certainly not the most interesting. I think it's most prestigious. And it's sometimes when you have something with a prestigious name to it, it does kind of cloud the reputation it's got. And so if from a purely scientific point, I think we've spent a lot of time going to other trenches. We've done Mariana about six times, but for various different reasons and different boats and different nationalities, whatever. There's been reasons for doing it, but it's no one trench represents all other trenches. And so it's the deepest one. Therefore, it's an outlier. It's not the same as the rest of them because it's deeper than them. The biggest problem in Mariana we've got is that one of the only big trenches in the world that does not lie along a coastline. So all that organic matter that comes into the surface that rains down is food. It's the only one that doesn't have it. The rest of them are somehow attached to or associated with the continental landmass.

• 36:25Speaker 05

  It's also quite low to the, which is near the equator. And so there's not a lot of food in the surface there anyway. So it's what we call oligotrophic, which means it's in an area of the ocean that doesn't have a lot of energy and it doesn't have any seasonality. And so there's lots of reasons why Mariana doesn't represent anything other than the fact it's super deep. So if the question you're trying to ask is what happens at mega deep depths? I guess it's your one. If it's the question is what happens in trenches or what happens across a massive depth range? There are many other places you need to go to as well. The analogy I always use is like, if you're trying to understand high altitude biology or high altitude flora and fauna, how much would Mount Everest tell you about every other mountain in the world? Not very much. He'll tell you a little bit about altitude, but he won't tell you anything about a mountain goat

• 37:10Speaker 05

  and Kilimanjaro, right?

• 37:11Speaker 03

  So do I get, John, in that case, it's the implication of what Alan's saying that the environment in Mariana is actually very static and constant compared to others?

• 37:24Speaker 06

  It depends on what timescale we're talking here. Now, everywhere in the deep ocean is changing as a result of impacts of human activity. So, climate change affects all of the ocean, including the deepest depths in the ocean, and it affects it in several different ways. I mean, we are getting warming of waters and that is getting deeper and so on. But fundamentally, for deep ocean, what's changing is the flow of oxygen that reaches the deepest parts of the ocean. So, all the animals that we've been talking about, they're animals, they need oxygen, the oxygen's dissolved in seawater. Where does that oxygen come from? Well, it dissolves from the atmosphere into the ocean in the polar regions, the surface, where dense, deep currents form and sink, and then they

• 38:08Speaker 06

  spill out across the ocean basins. So, life at somewhere like the bottom of the Arianna Trench, the oxygen that those animals are consuming began its journey into the deep, actually in the Antarctic, and it takes several hundred years for it to kind of flow and get there. And that flow is getting weaker as a result of climate change.

• 38:25Speaker 03

  Yes, although, does that mean that climate change is going to affect them in 300 years' time?

• 38:30Speaker 06

  It does, yes, indeed. And that change is already on its way from changes that we've made in the atmosphere. So, we already know that overall globally, the deep ocean will end up with about 10% less oxygen than it had in pre-industrial times. Now, it's very patchy and different bits will be affected more than some others, but overall globally, it's on track for 10% less than it had already. It's going to change the distributions of species around the world. Some can tolerate that, some can't, their distributions are going to shift. And that's a change that's already baked in, that's already happened, it's on its way to the deep ocean, it just hasn't reached the deepest places yet.

• 39:07Speaker 03

  Heather, it strikes me that when you're looking at something like the trenches, it involves a lot of different skills. It involves geologists, it involves engineers, it involves biologists, all sorts of people.

• 39:24Speaker 03

  How do they work together? Do they understand what the other is doing?

• 39:28Speaker 04

  Very much so. I think, I think I can speak on all of us, you know, like, I think the most rewarding expeditions have been the cross multidisciplinary ones. And each discipline, you know, thinks a little bit differently, you know, the, the engineers, to the geologists, to the physical oceanographers, to the bio geochemists. And I think that fusion and that sort of spark between the different disciplines and making, you know, hearing about their research questions and their concerns or their technological challenges or what aspects they are trying to overcome. And then you can sort of, oh, well, actually, you know, we, we do it this way, or, you know, you can take and learn from each other.

• 40:08Speaker 04

  But I mean, you know, I've worked, you know, over 20 years now with all these different disciplines and learned so much. And I think in order to undertake successful research, you need to be able to work together with everyone in these environments. And certainly I've learned a lot in terms of, you know, I'm a geologist, not an engineer. In terms of the, the challenges, in terms of how you build vehicles to put down to these sort of depths and things, you know, working with Alan, for example, as an engineer. Uh, you know, it's, it's fascinating and it's allowed me to think better and more strategically and more creatively about how to sort of address geological questions, you know, like, how can we get, um,

• 40:49Speaker 04

  physical samples and cores from these deep areas without using a big drill ship like the Japanese vehicle Chikyu? You know, trying to think a little bit more out of the box. But I think also in terms of the big discoveries, I think if you look back at how those expeditions and how the people on board have worked together, that's helped contribute to some of these big discoveries that we're making in the deep sea now as well.

• 41:13Speaker 03

  It's struck me in this discussion how remarkable the research into biology has been. Uh, John, I've got a question for you. How do you study these animals when presumably if you bring them up to the surface, they're not going to survive, are they?

• 41:32Speaker 06

  They they don't survive, no, they don't explode, okay, because of the pressure thing that we talked about in in reverse, okay, they're not, there's nothing in them to expand as they come up, if it's solid tissue and and liquid body fluids. But we can learn a lot from the specimens that that we do get, of course, we can look at the adaptations they've got, we can, we can look at what molecules are in their cells and and so on. These days, though, we're also able to preserve animals actually at the seafloor, which is really useful. So, for example, you can collect a specimen and you can process it in a way that its tissues are preserved in something that allows you to see what genes are actually switched on at the moment that you encountered it.

• 42:15Speaker 06

  So that, you know, otherwise, we we can do that with specimens we bring up, but of course, they'll have gone through a lot of changes on on the way up. But actually, being able to preserve things in situ is giving us really big insights in what we call genomics and transcriptomics, seeing what genes are actually being switched on in that organism, in its environment, to understand how it's adapted to the conditions down there.

• 42:35Speaker 03

  Historically, Alan, people have believed that this is an area of giant monsters and all sorts of mysterious creatures. Do you encounter that sort of attitude today, despite the fact that we now have a much better idea of what's down there and they're not giant monsters?

• 42:55Speaker 05

  Yes, all the time. It's one of the most common questions you get is about, questions about megalodon and stuff like that. And, you know, I think when you start looking into the energy in these systems, it could never ever support a large animal, especially not of that kind of size, but even bigger than a shoe is quite difficult to maintain of those kind of depth. So it's just all to do with education, I think, and the way in which deep sea is portrayed in the media and things like that. I think we can probably do it a bit more responsibly and stop referring to monsters and creatures and stop making movies about it. But then, you know, little snailfish aren't going to make a Hollywood movie, right? So, you know, they don't even have any teeth.

• 43:32Speaker 03

  Well, they did make a Disney movie about a clownfish, so maybe, maybe the snailfish could come next.

• 43:39Speaker 05

  Yeah.

• 43:40Speaker 03

  Who knows? I'm very interested in deep sea vents and deep sea mining. Is that something that you have to engage with, that debate about whether the minerals should be exploited in this way?

• 43:57Speaker 06

  I mean, I work primarily on deep sea vents, which we don't get in subduction trenches in the same, in the same way, these black smoker systems and so on. Yes, deep sea, that is one of the environments that's being targeted for a form of deep sea mining. There are others as well. People get very excited these days about the manganese nodules. That's a totally different environment, totally different set of ecological kind of challenges involved there. For deep sea vents, the active ones, which have these incredible colonies of, of species living around them, we don't actually need to do any more research to say that mining active deep sea vents would risk extinction of species. And we've been very clear to that to the international regulators. And I hope when they do draw up some kind of code for this activity in the future, that

• 44:40Speaker 06

  will be the top line for this environment, is that active deep sea vents must be protected.

• 44:44Speaker 03

  And one final question, is the Mariana Trench less interesting now because it's pretty well known what's, what's down there and it's not as active as, as the other trenches? Or will people still want to go down? Heather?

• 45:01Speaker 04

  I think as Alan hinted at, you know, just because it is the deepest, of course, you know, there's still going to be a lot of interest and activity down there. But I mean, for me, you know, the South Sandwich Trench, the Tonga Trench, the Kermdick Trench are much more interesting from a geological perspective in terms of the activity going on there. We're managing to document sort of volcanic pyroclastic density currents at, you know, in the, the rocks that have been deposited by those features at 8,000 metres wash depth, which has never been done before. So we're starting to look at new processes, we're getting little glimpses as to volcanic processes at depth in these environments now that hadn't been noticed before.

• 45:44Speaker 04

  So there's still a lot to be learned from these environments. But I think certainly sort of widening and working elsewhere and engaging with, with other researchers as well.

• 45:55Speaker 05

  There's also another way to look at it, because the Mariana is massive, right? If the volume of the Mariana is about the same as the volume of the Himalaya, and the size of a submersible might, let's say, is the size of a Land Rover.

• 46:04Speaker 04

  Yeah.

• 46:05Speaker 05

  So if you put a Land Rover on the Himalaya and said, like, how long is it going to take for you to document everything on this thing? It's going to take you a while. Right? So you could theoretically spend your entire life just working on that thing. But again, Within the bookends of it being this is what happens in the Mariana Trench, you can't necessarily make bigger statements about this is what happens in every trench, but it's still valid. And the Mariana Trench weirdly is actually five different areas. There are subducting sea much which partition it. So from an animal that challenged or deep, for example, could not get to the top of Mariana Trench without having it decompressed by thousands and thousands of meters. So technically it's five bins of really deep ones. So yeah, there's all sorts of interesting things to do.

• 46:42Speaker 03

  My thanks to John Copley, Heather Stewart and Alan Jamieson. And next week, it's the Roman arena and the role of gladiator fights in imperial politics. Thank you for listening.

• 46:55Speaker 08

  And the In Our Time podcast gets some extra time now with a few minutes of bonus material from Misha and his guests.

• 47:02Speaker 03

  So tell me, what did we miss out, John?

• 47:06Speaker 06

  I personally, I'm really fascinated in kind of like the inner space race that took people to the bottom of Mariana Trench for the first time. And the context for that, there were various private individuals who were designing these vehicles and engaged in this work and innovating and so on. And then the French Navy wanted to get involved and then they had a bit of a bust up. And eventually the US Navy got involved and bought up the technology at a time when they were real, during the Cold War, this is around about 1960, when they were really flexing their muscles publicly in terms of capability in the ocean. They sent a submarine underneath the North Pole for the first time. They surfaced one at the North Pole. They had the first circumnavigation submerged by a nuclear submarine

• 47:49Speaker 06

  and they wanted to be the people to get to the deepest point for the first time. So that whole story, I think, is a very interesting one.

• 47:56Speaker 03

  Sort of mirroring the space story about who gets there first.

• 47:59Speaker 06

  To some extent, the Soviet Union really weren't involved in sending people. I mean, they were sampling deep trenches in the late 1950s and looking at life down there, but they weren't looking at these kinds of demonstrations of capability in the same way.

• 48:14Speaker 03

  Heather, what did we miss out?

• 48:17Speaker 04

  I think the evolution of the Pacific Ocean as a whole is really interesting. So if we go back sort of two hundred, three hundred million years, we had a supercontinent called Pangaea and it was surrounded by a superocean called Pantalassa. And basically, the Pacific is the last remnant of that ancient ocean. And that's why it's so much older than the Indian and Atlantic. So they opened at two hundred million years ago as this supercontinent Pangaea started to break apart. That's when the Atlantic and the Indian Ocean started to to open. But what's really cool is that in the Northwest Pacific, actually just near the Mariana,

• 48:58Speaker 04

  is where they sampled the oldest oceanic crust in nineteen eighty nine. And it was drilled by a big international collaboration called the Ocean Drilling Programme. And that was a hundred and it proved rocks that are Jurassic in age one hundred and seventy million years old. And that is just fantastic. And I love the fact that the Pacific Ocean is this old ocean made of old geological rocks, oldest oceanic rocks that we have on our planet. And that and that's why the the Pacific Ocean technically is contracting as it's getting consumed, rather than the Atlantic and Indian that are still opening and widening at this time.

• 49:38Speaker 03

  So that's still the breakup of Pangaea?

• 49:40Speaker 04

  Yes, yeah. And I I I love that. I love that the geological timescale is still sort of trundling on and it's just this this conveyor belt of sort of motion. So if we think about plate tectonics and the earth being made up of these sort of jigsaw pieces all sort of moving relative to each other and some are sliding past one another, that's a sort of strike slip sort of margin, or one's being consumed by another, that's your convergent, that's your subduction areas and other ones are sort of where we get new crust being formed. And I just love that conveyor belt of evolution.

• 50:10Speaker 03

  John?

• 50:11Speaker 06

  The the thing that surprises me as a biologist, though, when I hear about this geological history is is that nevertheless, even though the Pacific is the oldest bit of ocean crust we've got, it's still really, to me, very young, you know, compared to three and a half billion year rocks on land in some places.

• 50:26Speaker 04

  Yeah, well, four point six billion year, yeah, so central of central Canada and even the northwest of Scotland, that's some of the oldest rocks on our planet is four point three million billion, sorry.

• 50:37Speaker 06

  But I think it shows how dynamic the ocean is.

• 50:39Speaker 04

  Yes.

• 50:39Speaker 06

  You know, that's that's the thing, is it's much more dynamic than the land.

• 50:43Speaker 04

  Yeah.

• 50:44Speaker 03

  But Alan, anything you feel we missed out?

• 50:48Speaker 05

  I've got a funny story about a party.

• 50:49Speaker 03

  Go on then.

• 50:50Speaker 05

  So, yeah, so Challenger Deep was not discovered in 1875, it was discovered in 1952. Right, but Challenger Two, right, so I read this book once, it was called The Hydrographer's Tale, and it's by a guy called Steve Ritchie. He ended up Rear Admiral Steve Ritchie, he was the highest ranking hydrographer in the Royal Navy. And he had done the soundings for the D-Day landings. He ended up on Challenger Two and he sounded what is now Challenger Deep with 10,000. And I remember talking to my boss, I used to work in Aberdeen for many years. I said to my boss, like, this guy's just the guy who discovered Challenger Deep. My boss said, yeah, he lives just up the road. I was like, you're kidding me. So I ended up at his 93rd birthday party. And he lived in a town called Colston and his family had been there for 200 years. And then we turned up thinking there's going to be this frail old man in this cottage.

• 51:31Speaker 04

  I really hope there's rum.

• 51:33Speaker 05

  Oh, there was lots of rum.

• 51:34Speaker 04

  Admiral's story, you know.

• 51:35Speaker 05

  He was wearing some like African poncho and his house is all like oil on canvas drawings of some harbour in Borneo somewhere. It was brilliant. Unfortunately, he died a couple of years later, but it was great to just, you know, it's like, I've actually met, went to the birthday party of the guy who discovered Challenger Deep.

• 51:47Speaker 03

  Let me get this straight, that Challenger Deep was only really identified by him?

• 51:53Speaker 05

  It's murky because someone gets the deep sounding which says there's something big there, but then refining just exactly where the deepest point is takes a little time.

• 52:01Speaker 06

  So Challenger Deep as a feature on a map turns up in 1877, okay, but it's not, you know, that's before there was a Mariana Trench or whatever, and it's just, and that's one measurement. And they've just drawn a kind of a circle around it and said, yeah, it's deep area.

• 52:13Speaker 03

  Did the Challenger, the original Challenger, did they have to have rope going down five kilometres or something?

• 52:19Speaker 04

  They did, I wrote it down actually, hang on, let me.

• 52:22Speaker 05

  It's a piano wire?

• 52:22Speaker 04

  Yeah, it was phenomenal, I was, they covered 70,000 nautical miles, but they had 144 miles of Italian hemp for the soundings that they were doing. And quite often they had a bucket on the end of that rope, so they could take like a little sample and that's of the sediment that was down there. But I mean, imagine have like keeping track of all of that wire and.

• 52:47Speaker 06

  And it wasn't actually the absolute cutting edge of technology at the time. So Lord Kelvin, the absolute polymath genius, 1872, he'd invented a wire sounding.

• 53:00Speaker 06

  Machine using piano wire to to measure depth. So what they they do is they lower a weighted line and they kind of look at the rate at which the line is paying out and and when it slows down, they assume the bottom of it is now touching the seabed. And it's, you know,

• 53:13Speaker 04

  In really deep water.

• 53:14Speaker 06

  In really deep water, yeah. The ocean currents can take it. And so anyways, that's why a lot of the early measurements are are way off for things. Lord Kelvin's piano wire machine is much more reliable. Now, he sent one to the HMS Challenger, but they couldn't get it to work properly. It was still a prototype. And so they just shelved it and they went with tried and tested hemp.

• 53:32Speaker 04

  They still had, was it 12 and a half miles of piano wire with them as well. You know, it's just.

• 53:37Speaker 06

  And and actually, that's that's something that because of the the popularity of upright pianos amongst the middle classes of the 19th century led to mass production of piano wire, which meant it was available in these huge lengths for ocean sounding.

• 53:51Speaker 04

  Yeah.

• 53:52Speaker 03

  What do we use for ocean sounding today?

• 53:54Speaker 04

  Acoustics. Sound. Yeah.

• 53:56Speaker 03

  But very, very accurate, right?

• 53:59Speaker 04

  Yeah. Yeah, yeah. So I mean, yeah, we know that, you know, Challenger Deep, for example, is 10,925 meters. Plus or minus six. Yeah, plus or minus six, you know, error margin, you know, and it's, you know, that's that's using sort of a sound to sort of it goes from the ship down to the sea floor, bounces off the sea floor and comes back up. What's interesting, it was the meteor in 1926 used sound to measure water depth for for scientific purposes. It had been used by the military pre 1926, but the first use for scientific purposes was actually in the South Atlantic, in the South Sandwich Trench. And it was an expedition and they measured, we

• 54:40Speaker 04

  went back and surveyed it in 2019, yeah. And we were within one meter of what they recorded in 1926. It was the Germans that had been out on. RV Meteor and it was, you know, that way that's just, it was almost a hundred years later.

• 54:59Speaker 05

  There is a stopgap in here.

• 55:00Speaker 04

  So it's meteor deep.

• 55:01Speaker 05

  In between the ropes and the acoustics, there was a thing called bomb sounding, which was brilliant. He'd stand on the back of the boat, you do like a stick of dynamite, you throw it off so it blows up on the surface. And there's a kid in the hull who pushes a stopwatch when the bang goes off and then pushes the stopwatch when he hears the echo.

• 55:16Speaker 04

  They're also trimming the length of the, the, the stock on the, the dynamite as well as they're doing it.

• 55:21Speaker 03

  Coming back from.

• 55:22Speaker 05

  You basically listen to the, the bang. So you, we come back, you know, the speed goes around 1500 meters per second. So you divide the time it takes between the bang and the echo by 1500 meters per second. That gives you the, the depth. And so some of the, there's a guy called, what's it, Bob Fisher in Kuhlenberg and these guys. They would sort of draw it based on these things. They would, and this hand drawn one in the Philippine trench. I think we went there and tell you what, it's not bad. It's not bad because given they're just lobbing dynamite off the back of the boat, right? There's a scientific paper where Bob Fisher stood on the back deck with a basically a case of TNT. Just like lighting off a cigar and just lobbing it into the ocean.

• 55:55Speaker 04

  I hate to be writing the risk assessment for that trip.

• 55:58Speaker 06

  And then eventually when we get echo sounding, you know, after bomb sounding, that was in part because of the Titanic. So there was a German inventor who after Titanic came up with a way, well, can we detect, you know, potential collision obstacles using sound looking ahead? And then people said, well, if we turn that vertically, we can use that to measure ocean depth.

• 56:16Speaker 03

  Got it.

• 56:16Speaker 05

  That's safer.

• 56:17Speaker 04

  Yeah. Just a little bit, yeah.

• 56:20Speaker 03

  Yeah. I was also very interested by the way, in the, the fact that the fiber optic cables are only at Challenger deep. And I, I can just imagine the type of the endless covert activity that is going on in places like this.

• 56:35Speaker 05

  It's not a little bit, it's everywhere.

• 56:36Speaker 03

  Yeah.

• 56:37Speaker 05

  It really is. And you don't want to get tangled up in it because you have no idea if it's a thousand meters long or 10,000 meters. But it's everywhere. We don't know if there's something on the end of it. So whenever you're going along there, you've got to keep your eye on it. And, and as soon as it's here, it's cut the dive, just move. We published all, we, we, we actually drew a map of it and. Try to recommend an area to not take a tethered or untethered vehicle because it's pretty bad.

• 56:57Speaker 03

  Why do you want to get rid of the, um, get rid of the fibre optic cable? Because presumably you can reuse it. If it's.

• 57:05Speaker 05

  Oh, there's lots of different reasons.

• 57:07Speaker 03

  Some of it's obviously.

• 57:08Speaker 05

  I'm not sure what I'm talking to who we think is doing it, but.

• 57:10Speaker 03

  Some of it's underwater cable, which is.

• 57:12Speaker 05

  Yeah, it's about getting live communication back to the surface. So there, there, there's ways in which you can do that by having a surface boy that gets winched below the surface or no one can see it. So you can, if you imagine you had a flotation device with a beacon on it a hundred metres under the surface and it's connected all the way to the bottom. Now you can listen to submarines coming out of Guam, which is, let's be honest, this is what's got something to do with that.

• 57:32Speaker 03

  Yeah.

• 57:32Speaker 05

  But you don't want someone being able to steal your listening device. So you have a little winch that then comes up for an hour, beams all your information back up and then pulls itself back down again.

• 57:39Speaker 03

  Right.

• 57:39Speaker 05

  And so there are those in the area, we think. Uh, but to, to get that technology right and to get stuff down there, fibre optic is the way to go. And the vehicle John talked about, the fibre optic R O V, we had that out and it was, it was, it was terrible. Uh, we happened to be there when it imploded, the whole thing imploded. It was just very experimental, but it was just a complete disaster. But all that fibre optic is gone now. It's all lying in the bottom of the sea again. So it's, it's, it's.

• 58:06Speaker 04

  I think that's what I was hinting at. It's just like today, you know, we don't have anything apart from submersibles that go that depth. Technology is moving forward and I think we need to move away from those sort of.

• 58:15Speaker 05

  Yeah, there was two solutions to it. One was super fine fibre optic. The other one was super heavy. Japanese went real big heavy stuff and then the Americans went super thin. And both turned out to be the wrong. And then someone's recently did a completely untethered one and that got lost as well. So it's not easy. So we've gone somewhere in between. Feels like the right thing to do.

• 58:33Speaker 04

  If it was easy, other people would, you know, we wouldn't be doing it as a group. Yeah.

• 58:37Speaker 03

  Yeah, yeah. I've come across quite a lot of fibre stuff in terms of drones as well now.

• 58:42Speaker 05

  Yes. That's the same stuff that was in the American, it was torpedo wire.

• 58:46Speaker 03

  That's what I see.

• 58:46Speaker 05

  It just falls out. So the faster you go, the better it works. If you stop and try to do anything, it breaks. Yeah.

• 58:52Speaker 04

  Which of course, from a research perspective, we're wanting to stop to pick up the samples of the, the communities and the rocks and, and things that are, that are down there.

• 58:59Speaker 03

  Yeah.

• 59:00Speaker 04

  Is it something that occurred to me is, um, when you were talking about the, the life down there. And I think it's one of the sort of funnier thing is, is the snailfish eating the amphipods, but of course amphipods eat soft things that have fallen down or decaying. So what do the snailfish do to stop the, the amphipods eating them from the inside out?

• 59:17Speaker 05

  They have an internal jaw, so they have two mouths. The big mouth at the front that is sucking an animal in. But if they just swallow it, the animal then just bore itself out of its stomach. So it has a second jaw inside its head that when it swallows it just grinds the animal to make sure it's dead.

• 59:29Speaker 03

  Oh my god.

• 59:31Speaker 04

  But what is really from a, from a non biologist sort of, you know, and that's what I was talking about when, you know, you pick up things from lots of different disciplines so that, you know, if you come across something unusual or noteworthy that isn't from your own discipline, you know that it's important.

• 59:47Speaker 03

  Right.

• 59:48Speaker 04

  But when I'm looking back at some of the video and watching the snail fish, so you see them sort of soak up the amphipod, but then as it's the second internal jaw is working, they sort of collapse and they have a little food coma on the seafloor as this is working, don't they? And you just see them. Yeah, they're just sort of sat, sort of, you know, doing a beach, well, what, what my family call a beached whale impression after you've had too big a meal. They're just all sort of sat on the seafloor going, oh crikey, you know, but really at least it means I'm not going to get consumed by my dinner from inside out, you know, it's just sort of funny things like that that keep you going. But I mean, I think as we're sort of exploring more and more of these environments and stuff, you know, that the discoveries that we're making is, is, makes it all worthwhile. It makes the sort of trips away, away from family and friends.

• 1:00:33Speaker 03

  But also the other thing that I failed to ask you about, which I should have done was about what the implications of the research are for human health. Because that was a fascinating aspect of it in terms of, I think it's to do with the enzymes and the protein folding. Is that right, John?

• 1:00:50Speaker 06

  Well, there are a lot of insights we can get from deep sea animals. I mean, I'm not so familiar with actual trench organisms, but it's something I, I keep an eye on. And, you know, deep sea life can inspire us in two different ways, actually for material science. So I was co-author in description of a species called the scaly foot snail, and it's teaching us how to make better solar panels, because it can create tiny crystals of a metal mineral at room temperature. And this is what people want to be able to do for solar panels. And now people have been able to recreate this process in the lab with kind of off the shelf ingredients. I also was involved in describing a species of deep sea shrimp, which has got tiny little bristles on it, which have inspired a new

• 1:01:30Speaker 06

  nano material that's fantastic for heat and sound insulation. So there's those sorts of things. And then there's a lot on the biomedical side. Um. One of the chaperone molecules that you get in a lot of deep sea life in laboratory studies, you know, can help to rescue human proteins that get bent out of shape, which involve in quite a few human diseases.

• 1:01:51Speaker 03

  Well, look, thank you all very much. This has been absolutely fascinating. Really appreciate it. Ah, Simon.

• 1:02:00Speaker 05

  Does anyone want tea or coffee or rum?

• 1:02:02Speaker 03

  No, I'm all right, thank you. The chances of finding a glass of rum in the BBC are actually less than zero.

• 1:02:09Speaker 05

  Thank you very much.

• 1:02:09Speaker 03

  Thank you, yeah. Brilliant, thank you. Thank you.

• 1:02:13Speaker 08

  In Our Time with Misha Glenny is produced by Simon Tillotson and it's a BBC Studios production.

• 1:02:20Speaker 09

  I'm Paul Kenyon and for Radio 4 and the History Podcast, this is Two Nottingham Lads.

• 1:02:27Speaker 10

  When the invasion happened, it was completely hell on earth with the sounds. The sad thing about war is people lose their empathy and their humanity.

• 1:02:35Speaker 09

  I want to know how two men from Nottingham ended up on opposite sides in the war in Ukraine and what became of them after a chilling encounter in a prison in Donetsk.

• 1:02:47Speaker 10

  Out of all the places in the world where I meet someone from Nottingham, it's in captivity, on two sides of the conflict.

• 1:02:53Speaker 09

  It's a story about how and why you pick a side in a war that's not your own. You can listen to Two Nottingham Lads first on BBC Sounds.

• 1:03:09Speaker 11

  Sometimes we all need an extra helping hand, especially with a tricky business problem you've been putting off. Claude is an AI for just that. It's the collaborator that understands your entire workflow and thinks with you, not for you. And Claude isn't just for quick questions. Hand it a whole task like turning a folder or scattered notes into a report, and it does the work and hands back something finished that you can open and edit. Claude can now draft a doc or deck right in front of you, and Claude Design now lives right inside Claude. Describe the website or prototype you're picturing, attach your design system, and it comes back in your own design language, ready to edit right on the canvas. It works with your files and the tools you already use, like Gmail and

• 1:03:52Speaker 11

  Slack. And whether you're debugging code at midnight, building a financial model, or strategising your next business move, Claude extends your thinking to tackle the problems that matter. For problems worth solving, get started with Claude at claude.ai/solve.

• 1:04:08Speaker 11

  That's Claude.ai/solve and check out Claude Pro, which includes access to all of the features mentioned in today's episode. Claude.ai/solve.