Johnston Atoll is a small, uninhabited island located in the central Pacific Ocean, about 1,400 miles southwest of Hawaii. It is part of the United States and is administered by the U.S. Fish and Wildlife Service. The atoll consists of four islands and is surrounded by a coral reef, making it a unique marine environment. Historically, Johnston Atoll was used by the U.S. military for various purposes, including as a nuclear testing site during the Cold War. Today, it is designated as a wildlife refuge, providing habitat for seabirds and other marine life. The atoll is also part of the larger Pacific Remote Islands Marine National Monument.