A 130 km2 atoll in the North Pacific Ocean about 1400 km (750 nm) west of Hawaii. There are four islands located on the coral reef platform, two natural islands, Johnston Island and Sand Island, which have been expanded by coral dredging, as well as North Island (Akau) and East Island (Hikina), artificial islands formed from coral dredging. Johnston is an unincorporated territory of the United States, administered by the US Fish and Wildlife Service of the Department of the Interior as part of the United States Pacific Island Wildlife Refuges. Sits atop Johnston Seamount.