Tom started back through the murk of the ocean bottom.

However, the voyage to the ocean bottom is still a challenging experience.

The wreck was still "visible on the ocean bottom" as of 2002.

"I saw them picked up off the ocean bottom myself."

People for years have tried to figure out how to explore the ocean bottom.

We would be mining fifteen miles down, or at the ocean bottom.

On the ocean bottom, sand dollars are frequently found together.

Before long nations may go to war over patches of ocean bottom.

This time the problem needed to be solved on the ocean bottom.

Before the mid-20th century, little was known about the ocean bottom.