Cold War History- In an underwater test, the U.S. detonated an atomic bomb at Bikini Atoll in the Pacific on 25 July 1946.

On 25 July 1946, the United States conducted the first-ever underwater nuclear explosion. Test Baker, detonated at the Bikini Atoll in the Pacific Ocean, was the fifth of over 2,000 nuclear explosions conducted to date. Half a century later in 1997, the International Atomic Energy Agency reported that the Bikini Atoll was still uninhabitable.