Map - Bikini Atoll (Bikini Atoll)

Bikini Atoll ( or ; Marshallese: Pikinni,, meaning "coconut place"), sometimes known as Eschscholtz Atoll between the 1800s and 1946 is a coral reef in the Marshall Islands consisting of 23 islands surrounding a 229.4 sqmi central lagoon. After the Second World War, the atoll's inhabitants were forcibly relocated in 1946, after which the islands and lagoon were the site of 23 nuclear tests by the United States until 1958.

The atoll is at the northern end of the Ralik Chain, approximately 530 mi northwest of the capital Majuro. Three families were resettled on Bikini island in 1970, totaling about 100 residents, but scientists found dangerously high levels of strontium-90 in well water in May 1977, and the residents were carrying abnormally high concentrations of caesium-137 in their bodies. They were evacuated again in 1980. The atoll is occasionally visited today by divers and a few scientists, and is occupied by a handful of caretakers.

The island's English name is derived from the German colonial name Bikini given to the atoll when it was part of German New Guinea. The German name is transliterated from the Marshallese name for the island, Pikinni, "Pik" meaning "plane surface" and "Ni" meaning "coconut tree", or surface of coconuts.