Submarine canyons are usually found in continental shelf.
A continental shelf is a part of a continental crust that lies under a shelf sea (an area of relatively shallow water).
Submarine canyons are narrow steep-sided valleys that cut into continental shelf or slope of the ocean. Submarine canyons are usually found in continental shelf where they begin as shallow valleys and later deepen away from land as they cut into the steeper continental slope. Different mechanisms such as erosion, turbidity currents and underwater landslides are thought to be responsible for the formation of submarine canyons.