continental shelf 
noun
The area of seabed around a large land mass where the sea is relatively shallow compared with the open ocean. The continental shelf is geologically part of the continental crust: [mass noun]: extensive areas of continental shelf...
- We live on a small island that stands on the continental shelf, a shallow area of seabed that joins Britain to mainland Europe.
- The continental shelf is a relatively shallow area of seabed over which a great deal of marine life is found.
- The continental slope connects the continental shelf and the oceanic crust.