The Hawaiian Islands, once known as the Sandwich Islands, form an archipelago of nineteen islands and atolls, numerous smaller islets, and undersea seamounts trending northwest by southeast in the North Pacific Ocean between latitudes 19° N and 29° N. The archipelago takes its name from the largest island in the group and extends some 1,500 miles (2,400 km) from the Island of Hawai i in the south to northernmost Kure Atoll. Excluding Midway, which is an unincorporated territory of the United States, the Hawaiian Islands form the U.S. State of Hawaii.

This archipelago represents the exposed peaks of a great undersea mountain range known as the Hawaiian-Emperor seamount chain, formed by volcanic activity over a hotspot in the earth's mantle. At about from the nearest continent, the Hawaiian Island archipelago is the most isolated grouping of islands on Earth.