Following World War II, the Cold War rapidly increased tensions between the United States and the Soviet Union, and both nations stepped up their nuclear weapons programs. At Bikini Atoll, in the remote Marshall Islands of the Pacific Ocean, America resolved to test its newest bombs.
In 1946, as part of Operation Crossroads, U.S. officials forcibly removed the 162 residents of the atoll in anticipation of two large nuclear blasts meant to test the bombs' effects on warships. This was the first-ever underwater nuclear explosion and everyone was curious to know what the effects would be.
The bomb (code-named Test Baker) displaced 2 million tons (1.8 million metric tons) of water, as well as generated an enormous mushroom-shaped cloud that arced far into the sky, as you can see in the photo, which was taken from an observation tower on Bikini Island 3.5 miles (5.6 kilometers) away [source: CNET].
More than six decades later, Bikini Atoll is still an unlivable mess wrecked by radiation. And the pictures from that day show exactly why [source: The Guardian].