A cinder cone and lava flows from various eruptions on the flank of Mauna Loa, the world's largest shield volcano in terms of volume and area covered, and one of five volcanoes that form the Island of Hawaiʻi in the U.S. state of Hawaii. Mauna Loa has probably been erupting for at least 700,000 years, and may have emerged above sea level about 400,000 years ago. Its magma comes from the Hawaii hotspot, which is the source of the Hawaiian Islands. The Mauna Loa Observatory and the Mauna Loa Solar Observatory are both located near the mountain's summit.Photo: Mila Zinkova