seabed , also: sea bed BrE
seafloor , also: sea floor

It was returned to the sea bed on the next dive.

Three weeks later, the plane was located on the sea bed.

It came from the place where our lead had found that hole in the bottom of the sea bed.

"An old sea bed," he said in an almost normal voice.

They are found in open water and on the sea bed.

How could she feel the sea bed below her, and know what lay concealed there?

But still we weren't through to the sea bed, though there was plenty of water about.

We must be very close to the sea bed now.

Here you can see the side of the ship crushed against the sea bed.

It is possible to walk across the sea bed of that time, 400 million years ago.