Even though it covers 70% of the surface of the Earth, we know very little about the ocean and its inhabitants.

In fact, we know more about the surfaces of the Moon and Mars than we do about the floor of the ocean.

In this episode of SciShow, Hank Green fills us in on seven surprising things that we don't know about the ocean by telling us a few things that we do know.

How curious are you about the ocean? Let us know in the comments!