Saline water covers approximately 361,000,000 km² (139,000,000 sq mi) of Earth's surface. This list shows the world's largest oceans and seas and their deepest points.

The greatest known depth is measured at the Mariana Trench of the Pacific Ocean, reaching as far as 11,033 meters. At the bottom of the trench the water column above exerts a pressure of 1,086 bars (15,750 psi), more than 1,000 times the standard atmospheric pressure at sea level.

The Puerto Rico Trench of the Atlantic Ocean takes second at 8,648m as its deepest point, at Milwaukee Deep. The Sunda Trench of the Indian Ocean takes third with a greatest known depth of 7,455m.