Bikini Atoll (also known as Pikinni Atoll) is an atoll in one of the Micronesian Islans in the Pacific Ocean, part of Republic of the Marshall Islands. It consists of 36 islands surrounding a 229.4-square-mile (594.1 km²) lagoon. As part of the Pacific Proving Grounds it was the site of more than 20 nuclear weapons tests between 1946 and 1958, including the first test of a practical dry fuel hydrogen bomb in 1952.