Johnston Atoll is comprised of four island: Johnston, Sand, East and North. Only Johnston Island is inhabited by humans. Sand, East and North Islands are "birds only" sanctuaries and are small spots of coral sand in the lagoon. Johnston itself is only 2 miles long, 1/2 mile wide and seven feet high. Rogers and Hammerstein were't thinking of this place when they did "South Pacific".
The atoll is located 800 miles southwest of Hawaii and is currently the home of the Johnston Atoll Chemical Agent Disposal System (JACADS).
Previously, Johnston Atoll was the primary testing site during the 1960s atmospheric nuclear testing. During World War II, it was an important aircraft refueling stop for planes on the way to the South Pacific.