Mauna Loa is the largest active volcano on Earth by volume and area. Its enormous shield shape spreads across much of Hawaiʻi Island, with broad, gently sloping sides built by fluid basaltic lava.
The volcano rises about 4,169 metres above sea level, but its base lies on the ocean floor, making its total height from the seafloor far greater. Mauna Loa’s summit contains a large caldera called Mokuʻāweoweo, and long rift zones extend northeast and southwest from it.
Mauna Loa is sometimes confused with Mauna Kea, which is taller above sea level, and with Kīlauea, which is often more visibly active. Mauna Loa’s eruptions can send lava down several different flanks, threatening communities and infrastructure on Hawaiʻi Island. Its most recent eruption began in November 2022 and ended in December 2022.