About 71 % of the Earth's surface is covered under the ocean. The ocean contains more than 97 % of the total water on Earth. It supports a vast variety of species from microbes to the largest-ever animal on Earth 'The Blue Whale'. Let us explore 21 informative and interesting facts about the Earth's Ocean.

1. According to scientists, about 90 percent of ocean species have not yet classified.
2. The deepest part of the ocean is the Mariana Trench which is about 11,000 meters deep.
3. The average depth of the ocean is about 3.6 km (or 2.2 miles).
4. As the pressure increases with depth, the pressure at Mariana Trench is more than a thousand times the standard atmospheric pressure at sea level.
5. The deepest point of the ocean is challenger deep in the Mariana Trench, only two people have reached there.
6. In Mexico, there is a river under the ocean. It is known as 'Cenote Angelita' or 'River in sea'.

7. The largest canyon in the ocean is 'Zhemchug Canyon' which is even deeper than the Grand Canyon.
8. The great barrier reef is the largest living structure in the world. It is located in the Coral Sea and can be seen from space.
9. There are internet cables laid under the ocean for over 1 million km.
10. There are about 3 million shipwrecks across the ocean floors.
11. If all the five million cubic miles of ice on Earth were to melt, sea level would rise by about 70 meters.
12. 50 - 80 percent of the Earth's atmospheric oxygen comes from marine plants.
13. There is a location in the ocean known as Point Nemo. It is the farthest location from any land area.
14. According to NOAA ( National Oceanic and Atmospheric Administration ), more than 80 percent of the Earth's ocean is not yet explored.
15. Veljko Rogošić holds the record for the longest distance ever swum without flippers in the open sea. He swam 225 km in 50 hours 10 mins.
16. Every year, About 700 million gallons of waste oil enter the ocean.
17. The ocean absorbs about 90 percent of the Earth's heat.
18. The rise and fall of sea levels ( Tides ) are caused by the gravitational influence of Sun and Moon.
19. There are many dead zones in the ocean. These are low-oxygen areas where marine life doesn't exist. Dead zones were natural but now some are caused by human activity.
20. The Pacific Ocean covers more than 150 million square km of Earth with an average depth of 4,000 meters. It is the largest and deepest ocean on Earth.
21. Light barely penetrates under one km from the ocean surface. There is complete darkness beneath that.