The largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east. At 165.2 million square kilometres (63.8 million square miles) in area, this largest division of the World Ocean – and, in turn, the hydrosphere – covers about 46% of the Earth's water surface and about one-third of its total surface area, making it as large as all of the Earth's land area combined.

The equator subdivides it into the North Pacific Ocean and South Pacific Ocean, with two exceptions: the Galápagos and Gilbert Islands, while straddling the equator, are deemed wholly within the South Pacific. The Mariana Trench in the western North Pacific is the deepest point in the Pacific and in the world, reaching a depth of 10,911 metres (35,797 ft).