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

But why not lay the power lines under the ground or on the sea floor?

In general, deep hot rock is thought to cause the sea floor to crack.

It does not move around as an adult but lives on the sea floor.

The sea floor will rise, millions of years from now.

Scientific surveys and studies of the sea floor began soon after.

We will open a container and put one of the weapons onto the sea floor.

It most likely spent its time crawling over or just above the sea floor.

But he now stared over the side as if it were possible to see the hidden sea floor.

The tallest stood almost two feet above the sea floor.

Blind for a moment, he rolled across the sea floor.