On July 25, 1946, the United States conducted the first-ever nuclear explosion of an atomic bomb underwater. The Baker test, detonated at Bikini Atoll in the Pacific Ocean, was the fifth of more than 2,000 nuclear detonation tests conducted to date. Of these tests, only a few, such as the Baker test, were conducted with underwater explosions, primarily to assess damage to ships and submarines; with the exception of a few in space, such as the Starfish Prime test in 1962, about three-quarters of the tests were conducted primarily underground, with the remainder in the atmosphere.
The device for the Baker nuclear test was suspended about 30 meters below the surface of the sea from beneath a ship; it detonated an atomic bomb equivalent to about 23 kilotons of TNT explosives. The Baker test followed the atmospheric Able test of July 1, 1946, both of which used the same type of protonium atom bomb as the Nagasaki bomb. They evaluated the effects of nuclear explosions on a fleet of ships and on animals by underwater detonation. Both the Baker and Able nuclear tests were part of Operation Crossroads, which involved the evacuation of approximately 42,000 personnel, 242 ships, 156 aircraft, and all 162 residents of Bikini Atoll.
During the Baker test, all pigs and most rats aboard the ships died from the blast or from radiation exposure. Of the approximately fifty-seven target ships, about eight were severely damaged, sinking or capsizing as a direct result of the explosion. Most of the remaining ships were exposed to high radiation. Despite decontamination efforts such as wiping and spraying the decks, the high radioactivity remained. The Baker nuclear test produced considerably more radioactivity than the Able. Most of the remaining ships were subsequently unable to operate due to overheating and were forced to sink.
It was not until 1947, the year after the Baker and Able nuclear tests, that a team of scientists and engineers conducted a scientific re-examination of the Bikini Atoll. Clearly, radiation had entered the Pacific food chain. Plankton glistened on the photographic dry plates. So did the intestinal tracts of the fish that ate them. Whether Bikini Atoll will return to the ecological balance it had before the Able nuclear test is uncertain in the short term. In 1998, almost 50 years and half a century after the tests, the International Atomic Energy Agency (IAEA) recommended that Bikini Atoll, where 23 nuclear tests had been conducted, should not be resettled without special radioactive decontamination. Residents of Bikini, Eniweck, Rongelap, and Utirik who were exposed to nuclear testing and radioactive contamination filed lawsuits against the U.S. government in the 1980's. The 1986 Free Association Agreement provides for compensation to the U.S. government for the health and environmental effects of nuclear testing.
