The most important, best known, most traversed and best provided for traffic of all the oceans on the globe, connecting, rather than separating, the Old World and the New; covers nearly one-fifth of the surface of the earth; length 9000 m., its average breadth 2700 m.; its average depth 15,000 ft., or from 3 to 5 m., with waves in consequence of greater height and volume than those of any other sea.