The part of a continent that is underwater is called the continental shelf.

Here's a breakdown:

* Continent: A large landmass on Earth.

* Continental Shelf: The gently sloping, underwater extension of a continent. It's typically shallow, with an average depth of about 130 meters (430 feet).

* Continental Slope: The steeper drop-off that marks the transition from the continental shelf to the deep ocean floor.

Think of it like a submerged platform extending out from the land. This area is rich in marine life and resources.