Palmyra Atoll (), also referred to as Palmyra Island, is one of the Northern Line Islands (southeast of Kingman Reef and north of Kiribati). It is located almost due south of the Hawaiian Islands, roughly one-third of the way between Hawaii and American Samoa. North America is about 3,300 miles (5,300 kilometers) northeast and New Zealand the same distance southwest, placing the atoll at the approximate center of the Pacific Ocean. The land area is 4.6 sq mi (12 km), with about 9 miles (14 km) of sea-facing coastline and reef. There is one boat anchorage, known as West Lagoon, accessible from the sea by a narrow artificial channel and an old airstrip; during WW2, it was turned into a Naval Air Station for several years and used for training and refueling. It was shelled by a submarine in December 1941, days after the Attack on Pearl Harbor, but was not the site of a major battle. Palmyra has, over time, had many of its islets merged together, so the actual amount of contiguous land depends on the tide and locations of sandbanks. For example, Strawn, Menge, and Cooper Islands are one contiguous island. Likewise, there are many shoals and coral heads on the atoll, which is ringed by a coral reef.
It is the second-northernmost of the Line Islands and one of three American islands in the archipelago, along with Jarvis Island and Kingman Reef. Palmyra Atoll is part of the Pacific Islands Heritage Marine National Monument, the world's largest marine protected area. The atoll comprises submerged sand flats along with dry land and reefs. It comprises three lagoons separated by coral reefs. The western reef terrace is one of the biggest shelf-reefs, with dimensions of 2 by 3 miles (3.2 by 4.8 km). Over 150 species of coral inhabit Palmyra Atoll, double the number recorded in Hawaii.
