The ocean is vast and deep
The oceans occupy 70 percent of the earth’s surface and contain most of its water. We know very little of the oceans, simply because they are generally too vast and deep to visit. We know more about the universe then the earth’s oceans.
The average depth of the world’s oceans is approximately 3.960 meters. That’s about thirteen Eiffel Towers stacked on top of one another. The oceans’ greatest depth is 11 kilometers (in the Marianas Trench, in the western Pacific). That’s higher then Mount Everest (8.848m) and similar to the height airliners fly.
Most of the ocean is eternally dark and cold. Sunlight only penetrates the uppermost 200 meters.
A cubic meter of water weighs about 1.000 kilograms. At the average depth of hydrothermal vents in the Pacific (2.700 meters), the weight (or pressure) of water is about 270 kilograms per square centimeter.