The continental shelf is a gently sloping and relatively flat extension of a continent that is covered by the oceans. Seaward, the shelf ends abruptly at the shelf break, the boundary that separates the shelf from the continental slope.

The shelf occupies only 7% of the total ocean floor. The average slope of the shelf is about 10 ft per mile (1.9 m per km). That is, for every one kilometer of distance, the shelf drops 1.9 m in elevation until the shelf break is reached. The average depth of the shelf break is 440 ft (135 m). The greatest depth is found off Antarctica (1,150 ft [350 m]), where the great weight of the ice on the Antarctic continent pushes the crust downward. The average width of the shelf is 43 mi (70 km) and varies from tens of meters to approximately 800 mi (1,300 km) depending on location. The widest shelves are in the Arctic Ocean...