Submarine linear mountain range on the floor of the South Pacific Ocean, roughly paralleling the western coast of South America.
The main portion of the rise lies generally about 2,000 mi (3,200 km) off the coast, and it lies about 6,000–9,000 ft (1,800–2,700 m) above the surrounding seafloor. The East Pacific Rise has a generally smooth and flattish surface, and it drops sharply away at the sides. It is composed largely of basic igneous crust, overlain or abutted by more or less flat-lying sediments.