the bikini atoll is a group of islands (an atoll) in the pacific ocean. it is part of the ralik chain. today, it is part of the marshall islands. it used to be known as eschscholtz atoll. the atoll is made of 23 islands, which have a surface area of . the lagoon is about by , and has a surface area of about . the lagoon has a depth of up to . the two biggest islands are bikini, at and enyu, at .