Written by a model from the transcript; not yet reviewed.
In the early 1980s, amid intense Cold War paranoia following a grounded Soviet submarine on Sweden's coast, the Swedish military began detecting a mysterious underwater noise on their hydrophones. Convinced it was the sound of invading Soviet submarines, the Navy chased phantom periscopes and dropped depth charges for over a decade, spending millions and creating diplomatic friction. But as two marine biologists eventually discovered in 1996, the classified sound was actually being produced by schools of herring releasing gas bubbles from a specialized canal connected to their swim bladders.
Lulu introduces the episode, framing it as a Cold War summer mystery.
Lulu reveals the archived story “Red Herring” and sets up the mystery.
The narrative of a Soviet submarine beached on Swedish shores and the national shock.
Swedish military’s efforts to locate and neutralize the submarine using hydrophones and bombs.
Repeated sonar detections of submarine sounds despite no physical evidence.
Magnus and Hakan propose that the sound could be herring bubbles, not submarines.
Swedish officials form a secret committee to investigate the mysterious sounds.
The team tests herring bubbles in controlled and wild settings to compare with the sonar sound.
The Navy confirms the sound originates from herring schools, ending the decade-long mystery.
A Nation on Edgestory
In October 1981, a Soviet submarine ran aground on Sweden's rocky coastline, plunging the neutral nation into a state of acute Cold War anxiety and daily fear of nuclear conflict.
Chasing Phantoms with Bombsdata
After hearing hydrophone detections in a Stockholm harbor in 1982, the Swedish military dropped depth charges for a month without finding a single submarine.
Listening to the Secret Soundinsight
After fifteen years of top-down secrecy, civilian scientists were finally brought into a secret naval base to listen to the classified typical sound, which sounded like distant Donald Ducks.
The Herring Anatomyinsight
Herring differ from most fish by having a canal running straight from their swim bladder to their anal opening, letting them push out gas bubbles.
Solving the Mysterystory
When placing a hydrophone into a net full of stressed herring, researchers finally recorded the exact typical sound that had haunted the Navy.
Submarines That Split Apartdebate
Military sonar operators watched objects on their screens split from one into two and four, leading them to hypothesize impossible shape-shifting Soviet submarines.
“But we here at Radiolab are offering you something different, which we are calling Cold War Summer.”
“We heard the typical sound.”
“The herring is different. The herring is special because they have a canal straight from the swim bladder to the anal opening.”
“The typical sound that had haunted the Swedish Navy for over a decade was not made by Soviet submarines.”
A deep-sea Cold War mystery with subs and bombs and science.
6,317 words · 7 speakers
Speaker names marked are inferred from speaking time and the show’s known hosts — they are not voice-verified.
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