9. The ocean itself might actually be alive
Environments are essentially giant recycling plants, in which all the nutrients in the system get reused. That's unlike an animal metabolism, which uses some nutrients and gets rid of the waste. It's why we need to keep eating to take in new fuel. But some who study the ocean have noticed that it doesn't perfectly reuse nutrients the way it should. Like us, it needs additional outside sources of nutrients. In other words, it basically is one giant superorganism.
And it is hungry.
10. It makes weird sounds we can't really explain
In case that fact doesn't induce any nightmares, here's some more terrifying info about the ocean: it makes sounds that are stranger and more baffling than a dubstep album. Take, for example, the "Bloop," a massively loud noise that, after analysis, was believed to be animal in nature. Which is fine, until you learn that there is no known animal on Earth big enough to create a sound that loud.
There have been several other intensely loud recordings collected from the ocean. In recent years, attempts to reexamine them have led some researchers to believe that original analysis was wrong, and the Bloop can be explained away as iceberg activity. Hopefully that's true, since the source of the sound is also the home of Cthulhu.