<P> The total mass of the hydrosphere is about 1.4 quintillion metric tons ( 7018140000000000000 ♠ 1.4 × 10 long tons or 7018150000000000000 ♠ 1.5 × 10 short tons ) , which is about 0.023 % of Earth 's total mass . Less than 3 % is freshwater ; the rest is saltwater , almost all of which is in the ocean . The area of the World Ocean is about 361.9 million square kilometers ( 139.7 million square miles ) , which covers about 70.9 % of Earth 's surface , and its volume is approximately 1.335 billion cubic kilometers ( 320.3 million cubic miles ) . This can be thought of as a cube of water with an edge length of 1,101 kilometers ( 684 mi ) . Its average depth is about 3,688 meters ( 12,100 ft ) , and its maximum depth is 10,994 meters ( 6.831 mi ) at the Mariana Trench . Nearly half of the world 's marine waters are over 3,000 meters ( 9,800 ft ) deep . The vast expanses of deep ocean ( anything below 200 meters or 660 feet ) cover about 66 % of Earth 's surface . This does not include seas not connected to the World Ocean , such as the Caspian Sea . </P>
<P> The total mass of the hydrosphere is about 1.4 quintillion metric tons ( 7018140000000000000 ♠ 1.4 × 10 long tons or 7018150000000000000 ♠ 1.5 × 10 short tons ) , which is about 0.023 % of Earth 's total mass . Less than 3 % is freshwater ; the rest is saltwater , almost all of which is in the ocean . The area of the World Ocean is about 361.9 million square kilometers ( 139.7 million square miles ) , which covers about 70.9 % of Earth 's surface , and its volume is approximately 1.335 billion cubic kilometers ( 320.3 million cubic miles ) . This can be thought of as a cube of water with an edge length of 1,101 kilometers ( 684 mi ) . Its average depth is about 3,688 meters ( 12,100 ft ) , and its maximum depth is 10,994 meters ( 6.831 mi ) at the Mariana Trench . Nearly half of the world 's marine waters are over 3,000 meters ( 9,800 ft ) deep . The vast expanses of deep ocean ( anything below 200 meters or 660 feet ) cover about 66 % of Earth 's surface . This does not include seas not connected to the World Ocean , such as the Caspian Sea . </P>
the hydrosphere composes approximately what percent of the earths surface
the hydrosphere composes approximately what percent of the earths surface
70.9
70.9