Living With the Bomb AUGUST 2005 Feature Main Page Photo Gallery On Assignment Learn More Forum Multimedia: 1946 Bomb Test Countdown to Detonation The lethal power of a nuclear bomb contrasts starkly with the deadpan delivery of the narrator in this video. On July 24, 1946, a bomb was set off at a depth of about 90 feet (27 meters) in the Bikini lagoon in the Marshall Islands. The second of two nuclear tests called Operation Crossroads, the bomb was similar to the one dropped on Nagasaki, Japan. The explosion displaced two million tons of water, excavated two million yards (1.8 million meters) of sediment from the lagoon floor, and sank nine unmanned ships. At 21 kilotons, such a blast would level downtown Washington, D.C., killing tens of thousands of people.