Ailuk Atoll (Marshallese: , ) is a coral atoll of 57 islets in the Pacific Ocean, and forms a legislative district of the Ratak Chain of the Marshall Islands. It is located approximately north from Wotje. Its total land area is only , but it encloses a lagoon with an area of . The major islets are: Ajelep, Aliej, Ailuk, Alkilwe, Barorkan, Biken, Enejabrok, Enejelar, Kapen and Marib. Most of the islets are on the eastern side of the atoll. The western and southern sides of the atoll have a nearly continuous submerged coral reef, with three main passes that lead in to the lagoon: Erappu Channel, Marok Channel and Eneneman Channel on the west side.