Arno Atoll (Marshallese: Arņo, [ɑ̯ɑɳˠːʌ͡ɔɔ̯]) is a coral atoll of 133 islands in the Pacific Ocean, and forms a legislative district of the Ratak Chain of the Marshall Islands. Its total land area is only 5 square miles (13 km2). Unlike most other atolls, Arno encloses three different lagoons, a large central one, and two smaller ones in the north and east. Its main lagoon encloses an area of 130.77 square miles (338.7 km2). At a distance of only 20 kilometres (12 mi), it is the closest atoll to the Marshall Islands capital, Majuro Atoll, and can be seen looking east from Majuro on a clear day at low tide.