This is equal parts fascinating and interesting and terrifying and kinda morbid.
It's a simulator of what it would be like to drown in the middle of the ocean. It's kind of like a HOLY BLEEP moment when you're done watching.
Or, you can watch someone else watch it. He kind of has a potty mouth though, so this is my NSFW LANGUAGE tag.
Enjoy. Or be afraid. Or whatever.