The sunrise colors the sky above the Kilauea Caldera and Mauna Loa in this view from Volcanoes National Park, Hawaii. Mauna Loa, one of the most active volcanoes on Earth, is also the largest, standing about 56,000 feet from its summit to its base on the ocean floor. (It stands 13,680 above sea level.) Mauna Loa means "long mountain." The steaming cliffs are visible at the caldera rim. Rain falls into cracks and is then turned into steam by the hot rocks below the surface.