Map - Johnston Atoll (Johnston Atoll)

Johnston Atoll is an unincorporated territory of the United States, currently administered by the United States Fish and Wildlife Service (USFWS). Johnston Atoll is a National Wildlife Refuge and part of the Pacific Remote Islands Marine National Monument. It is closed to public entry, and limited access for management needs is only granted by Letter of Authorization from the United States Air Force and a Special Use Permit from the U.S. Fish and Wildlife Service.

For nearly 70 years, the isolated atoll was under the control of the U.S. military. During that time, it was variously used as a naval refueling depot, an airbase, a testing site for nuclear and biological weapons, a secret missile base, and a site for the storage and disposal of chemical weapons and Agent Orange. Those activities left the area environmentally contaminated, and monitoring continues.

The island is home to thriving communities of nesting seabirds and has significant marine biodiversity. USFWS teams carry out environmental monitoring and maintenance to protect the native wildlife.

With the exception of USFWS activity, Johnston Atoll is a deserted 1300 ha atoll in the North Pacific Ocean, located about 750 nmi southwest of the island of Hawaiʻi, and is grouped as one of the United States Minor Outlying Islands. The atoll, which is located on a coral reef platform, has four islands. Johnston Island and Sand Island are both enlarged natural features, while Akau (North) and Hikina (East) are two artificial islands formed by coral dredging. By 1964, dredge and fill operations had increased the size of Johnston Island to 596 acres from its original 46 acre, increased the size of Sand Island from 10 to 22 acre, and added the two new islands, North and East, of 25 and 18 acres respectively.

The four islands compose a total land area of 2.67 km2. Due to the atoll's tilt, much of the reef on the southeast portion has subsided. But even though it does not have an encircling reef crest, the reef crest on the northwest portion of the atoll does provide for a shallow lagoon, with depths ranging from 3 to 10 m.

The climate is tropical but generally dry. Northeast trade winds are consistent and there is little seasonal temperature variation. With elevation ranging from sea level to 5 m at Summit Peak, the islands contain some low-growing vegetation and palm trees on mostly flat terrain, and no natural fresh water resources.