Ocean Regions: Ocean Floor - Deep Ocean Basin

The deep ocean basin, which is about 2.5 to 3.5 miles deep, covers 30 % of Earth's surface and has features, such as abyssal plains, deep-sea trenches and seamounts.

The abyssal plain is the flat, deep ocean floor. It is almost featureless because a thick layer of sediment covers the hills and valleys of the ocean floor below it.

Deep-sea trenches are the deepest parts of the ocean. The deepest one, the Marianas Trench in the South Pacific Ocean, is more than 35,000 feet (10,668 meters), or almost 6.6 miles (10.6 kilometers) deep. A Navy-owned submarine, the Trieste, still holds the record for diving to the bottom of the deepest part of the Marianas Trench, the Challenger Deep, on January 23,1960.