Submarine ridge lying along the floor of the central Atlantic Ocean. It is a long mountain chain running about 10,000 mi (16,000 km) in a general but curving north-south direction from the Arctic Ocean to the southern tip of Africa. The mountains sometimes reach above sea level, forming such islands or island groups as Ascension, the Azores, St. Helena, and Tristan da Cunha.

Learn more about Mid-Atlantic Ridge with a free trial on Britannica.com.