The continental shelf is an underwater landmass which extends from a continent. It is near the coastline and it is 120-200 meters deep.

The continental slope is the slope separating the continental shelf and the ocean depth.

An abyssal plain is an underwater plain on the deep ocean floor , between 3000 and 6000 meters deep.

An ocean ridge is an underwater mountain range.

An ocean trench is a long but narrow depressions of the sea floor. The oceanic trenches are the deepest parts of the ocean floor. The greatest ocean depth is in the the Mariana Trench, at a depth of 11,033 m below sea level.