The Island of Hawaii, also called the Big Island of Hawaii Island is a volcanic island and the eastern-most in the Hawaiian islands chain. With an area of 4,028 square miles, it is larger than all of the other Hawaiian Islands combined and is the largest island in the United States. The Island of Hawaii s administered as the County of Hawaii within the state of Hawaii. The county seat is Hilo. Traditionally, Hawaii is known as the "Big Island" to reduce confusion between Hawaii Island and the state. You’ll find 11 of the world's 13 climactic zones on this island - everything from lush rain forests to arid deserts, black sand beaches to snow-capped mountaintops. Kileaua Volcano in Hawaii Volcanoes National Park is the world’s most active volcano. With an elevation of more than 33,000 feet, Mauna Kea is the world’s tallest mountain measured from the ocean floor.