Anacapa Island is a small volcanic island located about 11 miles (18 km) off the coast of Port Hueneme, California, in Ventura County. The Island is composed of a series of narrow islets 6 mi (10 km) long, running in a mostly east-west orientation, 5 mi (8 km) east of Santa Cruz Island. The island is composed of three islets: East, Middle and West Anacapa, collectively known as the “Anacapas” by some authors. The islets have precipitous cliffs, dropping off steeply into the sea. East and Middle Anacapa have fairly level areas at their tops, but West Anacapa is wider and reaches an altitude of 930 ft (283 m). Middle Island reaches an altitude of 325 ft (99 m) and East Island is 250 ft (76 m) at its highest point. All three islands total 699 acres (283 ha), or about 1.1 square miles (2.8 km2).
Anacapa is part of the Channel Islands archipelago (island chain), and is part of the Channel Islands National Park. It is the smallest of the northern islands. The islands are defined by the United States Census Bureau as Block Group 8, Census Tract 36.04 of Ventura County, California. The official 2000 census population was 3 permanent residents (Ranger Station in the eastern part of East Island), and the total land area was 2.947 km2 (1.138 sq mi).The highest peak is Summit Peak 2 on West Island, 930 ft (283 m).
East Island’s most notable natural feature is Arch Rock, a 40-foot (12 m)-high natural bridge.