Bikini Atoll is an atoll, or ring of islands, in the Pacific Ocean, considered part of the region of Micronesia, and part of the Republic of the Marshall Islands. The atoll is made up of 36 islands around a 229.4-square-mile (594.1 km2) lagoon. Between 1946 and 1958, twenty-three atomic bombs were detonated there, as the atoll was part of the Pacific Proving Grounds, one of the world's earliest nuclear testing sites. Bikini Atoll is located in the northwest region of the Republic of the Marshall Islands, which gained nominal independence from the United States in 1981.
Between its initial colonization around 2,000 years ago and 1946, Bikini Atoll was a quiet, lightly populated, and peaceful atoll. In 1946, about 167 indigenous inhabitants were relocated to Rongerik Atoll, about 124 mi (200 km) east of Bikini Atoll, where most of them or their descendants remain today. Shortly thereafter, nuclear testing began with Operation Crossroads, which included shots Baker and Able, the world's fourth and fifth nuclear explosions, respectively. These were the first nuclear explosions at sea, and the first to generate acute radioactive fallout, which contaminated the target ships used for the exercise. The blasts generated so much energy that the submarine craters they created consisted of sand too fine for crabs to walk on.
Bikini Atoll was the site of the largest nuclear explosion ever performed by the United States, Castle Bravo, on 1 March 1954. This 15 megaton blast was 2.5 times larger than expected, and produced a crater over a mile wide, which can be seen in satellite images of the atoll. The blast caused considerable nuclear fallout over a wide area, including the atoll itself, but also neighboring atolls and the crew of a Japanese fishing boat, Lucky Dragon 5. This created a major scandal with the Japanese, and the event inspired the 1954 film Godzilla, in which a nuclear test awakens and mutates a huge reptilian monster, which subsequently attacks the Japanese mainland until it is vanquished.
Bikini Atoll is also known as the atoll that inspired the name of the bikini swimsuit, which was created just a few days after the first atomic tests there. The swimsuit was given the name because the excitement it was expected to generate would be on par with the energy produced by a nuclear device.