Everest dominates Mauna Kea in prominence. In fact, Everest dominates any peak on Earth in prominence, since it's the tallest peak. By the mathematical definiti

Everest dominates Mauna Kea in prominence. In fact, Everest dominates any peak on Earth in prominence, since it's the tallest peak. By the mathematical definition of prominence, the dry prominence of Everest is always measured from the deepest point on Earth, the Challenger Deep. If you dug a moat around Mauna Kea, it would indeed increase its prominence, but would not affect the prominence of Everest. Until you dug the moat deeper than the Challenger Deep (about -11,000 m), at which point the dry prominence of Everest would start to be measured from the bottom of your moat and not Challenger Deep. At this point, digging the moat any deeper would increase the prominence of both Everest and Kea by equal amount, but Everest as the higher mountain would nevertheless always dominate Kea.