About the Refuge

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Johnston Atoll, one of the most isolated atolls in the world, is located in the central Pacific Ocean, between the Hawaiian Islands and the Line Islands. The formation of Johnston Atoll began about 70 million years ago, when repeated submarine volcanic eruptions built up layer upon layer of basaltic lava from the floor of the ocean to its surface. Geologically, Johnston anchors the northern end of the Line Islands Ridge, although its coral reef biota resembles Hawai‘i's marine fauna and flora.


Over millions of years, the island slowly eroded and subsided. As the island sank beneath the surface of the ocean, corals around its fringes continued to grow. Today, Johnston Atoll is a broad, shallow platform of about 50 square miles with four islands - Johnston, Sand, North, and East, and a marginal, emergent reef only on its northwest side.

This atoll was discovered accidentally in 1796 by Captain Joseph Pierpoint when his ship, the American brig Sally, ran aground. However, it was not until 1807 when the crew of the frigate HMS Cornwallis sighted the atoll and named the larger island after that ship's captain, Charles J. Johnston.

In 1926, Johnston Island and Sand Island were designated as a federal bird refuge. In 1934, President Roosevelt placed the atoll under U.S. Navy control, but retained its status as a refuge. In 1936, the Navy began the first of many changes to the atoll. By 1964, dredge and fill operations had increased the size of Johnston Island to 596 acres from its original 46 acres, also increased Sand Island from 10 to 22 acres, and added two new islands, North and East of 25 and 18 acres.

On January 6, 2009, the Pacific Remote Islands Marine National Monument was established, which includes Johnston Atoll National Wildlife Refuge within its boundaries. By Secretary’s Order, the boundaries of the refuge were expanded out to 12 nautical miles from the mean low water line. The emergent lands at Johnston Atoll are still managed by the U.S. Air Force, but when their administrative jurisdiction is terminated, they will be managed as a national wildlife refuge. For more information, please visit the Pacific Remote Islands Marine National Monument website.