Castle Bravo: America's Deadliest Nuclear Mistake

REDACTED: Declassified Mysteries with Luke Lamana

Wondery | Ballen Studios

History, True Crime

4.3 • 668 Ratings

🗓️ 12 August 2025

⏱️ 37 minutes

🔗️ Recording | iTunes | RSS

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Summary

On March 1, 1954, a Japanese fishing boat called the Lucky Dragon No. 5 was sailing near the Marshall Islands when its crew was caught in the fallout of a secret U.S. hydrogen bomb test. Code named Castle Bravo, the test released far more radiation than scientists had anticipated, contaminating not only the fishermen but nearby islanders, all without warning. Later labelled the “worst nuclear test in U.S. history,” Castle Bravo exposed the recklessness and secrecy at the heart of the Cold War arms race.

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Transcript

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0:00.0	Wonderry Plus subscribers can listen to Redacted, declassified mysteries early, and ad-free right now.
0:06.9	Join Wondry Plus in the Wondry app or on Apple Podcasts.
0:19.1	Before sunrise on March 1st, 1954,
0:23.0	29-year-old Japanese fishing master, Yoshio Masaki, stood on the deck of his boat.
0:29.1	He was near the Marshall Islands, halfway between Hawaii and Australia.
0:33.7	Most of his crew were downstairs in their bunks, trying to get some rest.
0:37.4	They just finished releasing the ship's hundreds of fishing lines, a back-breaking task that began
0:42.3	every morning at 3 a.m.
0:44.3	Masaki was tired too, but he still had work to do.
0:47.3	It had been a rough couple of weeks for his crew.
0:50.3	Their ship was called Lucky Dragon No. 5, but they hadn't had much luck on their fishing expedition.
0:56.4	They'd been caught in a few storms and almost swallowed up by the choppy seas.
1:01.2	Masaki and his men couldn't wait to get back to their home port of Yaizu.
1:05.2	But first, they had to do one final fishing run.
1:08.7	Masaki looked up at the inky sky through a brass telescope.
1:12.2	He spotted Antares and used the star to calculate the boat's location.
1:16.6	He was glad to see they were on the right track.
1:19.2	They had decided to go south, where the seas were calmer, in search of yellowfin tuna.
1:24.5	The ship's radio man had warned Masaki that atomic tests had recently been conducted
1:28.8	in the area. There was a restricted American military zone nearby. So they'd charted their
1:34.1	course to stay about 90 miles outside of it. Masaki wanted to steer clear of water that might be brimming
1:39.7	with toxic radiation. He set his navigation device down, thinking about how nice it would be to sleep in his own bed again
	...

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