Mountains Beneath the Ocean

Long mid-ocean ridges, individual submarine volcanoes, and entire mountain chains lie beneath the ocean. For example, Hawaii’s Mauna Kea rises about 10.2 km from its base on the ocean floor to its summit—more than Everest’s elevation above sea level. Yet having a map does not mean people have seen every area up close: visual imaging has covered only a tiny fraction of the deep seafloor.