Which ocean has the greatest average depth?

The Pacific Ocean has the greatest average depth of any of Earth’s five conventional oceans. Its average depth is about 4,280 meters, although the exact figure varies slightly with the boundaries and measurement method used.

The Pacific is also the largest ocean and contains the Mariana Trench, including Challenger Deep—the deepest known point on Earth. That combination of enormous area and very deep trenches gives the Pacific the greatest total volume of ocean water as well as the greatest mean depth.

Portuguese explorer Ferdinand Magellan named it “Mar Pacífico,” meaning “peaceful sea,” after encountering relatively calm conditions during his 1521 crossing. Earlier, Vasco Núñez de Balboa had called it the “South Sea” after sighting it from Panama in 1513.

The Atlantic and Indian oceans are also very deep on average, but neither matches the Pacific. The Arctic Ocean is much shallower overall, despite containing deep basins and trenches in some regions.