Estimate the weight of all the oceans on Earth. The volume of a shell of radiusRE and thickness d isVshell = 4RE2d. The radius of the EarthRE is 6,371 kilometers (3,959 miles) and the average ocean depth, d, is 3,800 meters (12,467 feet). You can take the density of water to be = 1 g/cm3. You can estimate that 75% of Earth's surface is covered by the oceans. The mass of the oceans should then be given by M = V , where is the density of water and V the volume of the oceans.