Ailinginae Atoll (Marshallese: , ) is an uninhabited (due to Castle Bravo nuclear testing) coral atoll of 25 islands in the Pacific Ocean, on the northern end of the Ralik Chain of the Marshall Islands. Its total land area is only , but it encloses a lagoon of . It is located approximately west of Rongelap Atoll. The landscape is low-lying with only the top 3 metres above sea level. The two entrances into the lagoon are 'Mogiri Pass' and 'Eniibukku Pass'. These are 0.9 and 0.3 miles wide respectively.