While it might seem counterintuitive, Mauna Kea is considered the largest mountain because we measure its height from its base on the ocean floor to its summit. From this perspective, Mauna Kea rises over 10,200 meters (33,474 feet) from its base, making it taller than Mount Everest.

However, when measuring from sea level, Mauna Kea's summit is only 4,205 meters (13,796 feet) high. This is because a significant portion of its base is submerged beneath the Pacific Ocean.