Hawaii is an island state in the Western United States, about 2,000 miles from the U.S. mainland in the Pacific Ocean. It is the only U.S. state outside North America, the only one which is an archipelago, and the only one in the tropics. Hawaii consists of 137 volcanic islands that comprise almost the entire Hawaiian archipelago. Spanning 1,500 miles, the state is physiographically and ethnologically part of the Polynesian subregion of Oceania.