Mauna Kea on Hawaii’s Big Island only pokes 4,207 metres out of the Pacific Ocean. That sounds modest. But the volcano keeps going down through the water and into the seafloor for around 6,000 more metres before it reaches its base.
Add it all up and Mauna Kea stands more than 10 kilometres from base to summit - over a kilometre taller than Mount Everest. By that measurement, it’s the tallest mountain on Earth, even though Everest still wins for height above sea level.
Mauna Kea is so massive that the seafloor underneath it has actually been pushed down by its weight. Its peak is dry, freezing, and almost in space - the world’s best telescopes sit at the top, hunting for distant galaxies in clear thin air.
