Operation Crossroads was a series of nuclear weapon tests conducted by the United States at Bikini Atoll in mid-1946. It was the first test of a nuclear weapon after the Trinity nuclear test in July 1945. Its purpose was to investigate the effect of nuclear weapons on naval ships.
Crossroads consisted of two detonations, each with a yield of 23 kilotons: Able was detonated at an altitude of 520 feet (158 m) on July 1, 1946; Baker was detonated 90 feet (27 m) underwater on July 25, 1946
To prepare the atoll for Crossroads, Bikini's native residents agreed to evacuate the island of Bikini. Many were moved by the LST 861 to the island of Rongerik. Later, in the 1950s, a series of large thermonuclear tests rendered Bikini unfit for subsistence farming and fishing. Because of radioactive contamination, Bikini remains uninhabited as of 2011, though it is occasionally visited by sport divers. Although there are claims that participants in the Crossroads tests were well protected against radiation sickness, the Oscar-nominated documentary Radio Bikini showed footage of Navy sailors wearing little or no protection during their inspection of the target ships only hours after the explosions, even though some of the observer ships were caught in the fallout of the Baker explosion. In addition, the documentary revealed that Navy ships used contaminated water from the area for drinking and bathing purposes after the blast. One study showed that the life expectancy of participants was reduced by an average of three months.