Mount Everest is not the tallest mountain on Earth — Mauna Kea is

Ask anyone to name Earth’s tallest mountain and they’ll say Everest. They’d be half right. Everest’s summit sits 8,848.86 m (29,032 ft) above sea level, higher into the sky than anywhere else. But “highest above sea level” and “tallest, base to summit” are two different contests — and Everest only wins the first.

Mauna Kea, a dormant shield volcano on Hawaii’s Big Island, pokes a modest 4,207 m (13,802 ft) above the Pacific. The trick is that its base isn’t at the shoreline. The mountain keeps going down, roughly 6,000 m to the seafloor it was built on. Stack the hidden part on the visible part and Mauna Kea stands about 10,211 m (33,500 ft) tall — more than a kilometer taller than Everest from foot to peak.

Of Mauna Kea’s roughly 33,500 feet of total height, only about 13,800 feet ever sees daylight.

The reason is simple physics. Everest is pushed up by colliding continental plates; Mauna Kea was poured out as lava onto deep ocean floor, so most of its bulk is submerged. In 2021 explorer Victor Vescovo and Clifford Kapono made the first continuous “full ascent,” diving to the seafloor base and climbing to the summit — a vertical gain about 5% greater than Everest’s sea-to-summit rise.

So Everest keeps its crown as the highest mountain. The tallest one is hiding underwater off the coast of Hawaii.