Hawaii is the only state made up entirely of islands and located on an archipelago in the central Pacific Ocean, southwest of the continental United States. The capital is Honolulu, which is on the island of Oahu. The state encompasses nearly the entire volcanic Hawaiian Island chain, which comprises hundreds of islands spread over 1,500 miles (2,400 km) with the eight "main islands" being (from the northwest to southeast) Niihau, Kauai, Oahu, Molokai, Lanai, Kahoolawe, Maui, and Hawaii. The last is by far the largest, and is often called the "Big Island" or "Big Isle". This archipelago is physiographically and ethnologically part of the Polynesian subregion of Oceania.