Mauna Kea, Mauna Kea volcano, Mauna Kea tallest volcano in the world, Mauna Kea is the tallest volcano on Earth and its summit hosts the world&#039;s highest observatory. Photo: Wikipedia, largest volcano, largest volcano around the world, world largest volcano, Which Volcano is the World&#039;s Largest? Three volcanoes share this title. Tamu Massif the most massive. Mauna Kea is the tallest. Ojos del Salado is the highest.