Question

A long narrow, steep-sided depression on the ocean floor is called

Answer 1

Answer:

A long narrow, steep-sided depression on the ocean floor is called Deep sea trench

Answer 2

A long narrow, steep-sided depression on the ocean floor is called oceanic trench.

Oceanic trenches  are also called deep-sea trenches. They usually get formed in locations where a tectonic plate gets subducted under another plate.

The deepest oceanic trench is the Mariana Trench. It is situated in the western part of the North Pacific Ocean to the east of the Mariana Islands.