Benthic is an adjective that means occurring at the bottom of a body of water. 

The Greek word ‘benthos.’ (VEN thos) means ‘depth of the sea.’ Since the early 20th century, our word of the day has been used to describe the landscape and activity at those depths. Here’s an example:

One of the joys of diving is being able to observe all those creatures on the ocean floor. You’d be shocked at all the strange-looking animals you’d find engaged in benthic activity.