Some good ambient!
I think the title suits the song well. To me it sounds like you're under the ocean and visualizing things.
First it sounds almost hostile and threatening, but gets lighter. The heart beat thing sounded cool.
And then comes a good extro. Sounds like you're either sinking to the bottom of the ocean or floating to the surface.
I like this song, it's got variation in both sounds and moods. It also has good depth. Well done with creating a cool atmosphere, Leo!