It's no surprise that early Hawaiians called this massive volcano Mauna Loa, or "Long Mountain." It's one of two volcanoes that make up Hawaii Volcanoes National Park, rising more than 13,000 feet above sea level and extending another 42,000 feet below the ocean and bottom. Sea. In fact, Mauna Loa is so huge that it covers half the size of the island of Hawaii; And it's large enough to accommodate all the other Hawaiian islands combined!