Kure Atoll (; ; ) or Ocean Island is an atoll in the Pacific Ocean west-northwest of Midway Atoll in the Northwestern Hawaiian Islands at . A coral ring six miles across encloses a lagoon several meters deep. The only land of significant size is called Green Island and is a habitat for hundreds of thousands of seabirds. A short, unused and unmaintained runway and a portion of one building, both from a former United States Coast Guard LORAN station, are located on the island. Politically, it is part of Hawaii, although separated from the rest of the state by Midway, which is a separate unorganized territory. Green Island, in addition to being the nesting grounds for tens of thousands of seabirds, has recorded several vagrant terrestrial birds, including snow bunting, eyebrowed thrush, brambling, olive-backed pipit, black kite, Steller's sea eagle and Chinese sparrowhawk. It is currently managed as a Wildlife Bird Sanctuary by the State of Hawaii's Department of Land and Natural Resource–Division of Forestry and Wildlife as one of the co-trustees of Papahānaumokuākea Marine National Monument with support from the Kure Atoll Conservancy.
Kure is seasonally inhabited by small crews of two to eight volunteers and biologists who work to restore and manage the native ecosystem.
Kure was discovered in the 19th century and was a common site of shipwrecks. In the late 20th century it was home to a radio base that supported location finding, and in the 21st century it is mostly a nature reserve.
Geography and ecology
The International Date Line lies approximately 100 miles (87 nmi/160 km) to the west. Although located to the west of Midway Atoll, Kure Atoll has a time zone 1 hour ahead at UTC−10:00 (the same as the rest of Hawaii). Kure is the northernmost coral atoll in the world. It consists of a 6-mile (10 km) wide nearly circular barrier reef surrounding a shallow lagoon and several sand islets. There is a total land area of , with Green Island on the southeast side. A growing number of Hawaiian monk seals (Monachus schauinslandi) haul out on its beaches. The polynesian rat (Rattus exulans) has been on the island since it was discovered.
The coral reef is a rough ring shape about six miles across and has two islands within, Sand Island and Green Island. Green Island is in the southeast quadrant of the ring, with an area of 235 acres. Sand Island is about one acre in size and lies to the west of Green Island. Sand Island is not known to have plant life.
Green Island has a wide variety of vegetation including groves of Beach Naupaka (Scaevola taccada), which are a popular habitat for birds. Another type of tree on Green Island is the heliotrope tree (Tournefortia argentea), there are two groves of ironwood trees (Casuarina equisetifolia), and other common plants are Verbesina and Bermuda grass. A survey of plant life in 2001 counted about 50 different species of plant on Green Island.
Green Island is roughly triangular with a point to the north and with a northwest beach extending down to a western point. The east side arcs down from north point and the shore includes east beach, southeast beach, and south beach, which arcs around to West point on the south side of the island. Overall Green Island is 1.5 miles long and up to half a mile wide. The highest point is 25 feet.
Seabirds known to be at Kure in one survey: Black-footed Albatross (Diomedea nigripes) Laysan Albatross (Diomedea immutabilis) Wedge-tailed Shearwater (Pufinus pacificlcs) Red-tailed Tropic-bird (Phaethon rubricauda) Blue-faced Booby (Sula dactylatra) Brown Booby (Sula Leucogaster) Red-footed Booby (Sula sula) Great Frigate-bird (Fregata minor) Gray-backed Tern (Sterna lunata) Sooty Tern (Sterna fuscata) Noddy Tern (Anous stolidus) White-capped Noddy Tern (Anous minutus) White Tern (Gygis alba)
As of 2002, 92 species of algae have been discovered in the central lagoon of Kure Atoll.