Island (pop., 2000: 876,165) of Hawaii, U.S. Situated between the islands of Kauai and Molokai, it occupies 607 sq mi (1,574 sq km) and is the third largest and most densely populated of the Hawaiian Islands. Of volcanic origin, it has two parallel mountain groups, the Koolau Range and Waianae Ranges, which are connected by a central plateau. It is the site of Honolulu, Pearl Harbor, and Waikiki. Military installations, tourism, pineapples, and sugar are important to its economy.