ocean bottom

At different times portions of what was once the ocean bottom have been lifted and have become land.

We have waterproof, pressure-resistant bodies for working down on the ocean bottom.

Below depths of from fifteen to eighteen thousand feet the ocean bottom is sheeted with red or chocolate colored clay.

He snapped his notebook shut and stared at the uneasy ocean bottom.

The next step may have been the "discovery" of the ocean bottom and the tapping of an hitherto unexploited supply of food.