 The mass of the oceans is approximately 1 @.@ 35 × 1018 metric tons , or about 1 / 4400 of Earth 's total mass . The oceans cover an area of 3 @.@ 618 × 108 km2 with a mean depth of <unk> m , resulting in an estimated volume of 1 @.@ 332 × 109 km3 . If all of Earth 's crustal surface was at the same elevation as a smooth sphere , the depth of the resulting world ocean would be 2 @.@ 7 to 2 @.@ 8 km . 
