Kingman Reef is a largely submerged atoll located in the North Pacific Ocean. It is a part of the United States Minor Outlying Islands, which is an unincorporated territory of the United States. The reef was named after an American captain, W. Kingman, who discovered it in 1874. Kingman Reef is uninhabited and serves as a wildlife refuge. The atoll is about 9.9 square miles (25.7 square kilometers) in size, with the lagoon covering approximately 77 square miles (200 square kilometers). The reef is made up of coral and sand, with its highest point rising just 5 feet (1.5 meters) above sea level. Kingman Reef is located along the Pacific Remote Islands Marine National Monument, which is managed by the U.S. Fish and Wildlife Service. Access to the atoll is restricted, and permits are required for any visitation.