At more than 4000 square miles, the island of Hawaii is the largest island in the Hawaiian archipelago, hence its nickname - the Big Island - and it's the newest. It is, in fact, still forming land mass due to the near continuous eruption of the Kilauea volcano. From it base on the Pacific Ocean floor to its twin volcanic summits of Mauna Kea (extinct) and Mauna Loa (dormant), the island of Hawaii rises more than 30,000 feet and is actually the tallest mountain on earth. Mt Everest in the Himalayas does reach a higher altitude, but its base is a mere 8000 feet below its peak.
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