Of course in order to save yourself you have to know the difference between an anchor and a life preserver. Some don't. Why?

Instead of seeking a life preserver they reach out for anchors and then as they are going down down down sure to drown the think everything will devine fine. Hallucinating?

So I know if you come up to fast from the depths a diver gets the bends. What happens if you go do too fast? Anything?

What is "TOO FAST"? Timewise?