What is the name of underwater event where they go on weights and float back up?

Question

I have seen a show on discovery channel. The people went down deep under water to where pressure is kind of high on round disk weights. The people floated back up and said in commentary part they regulate their speed so their lungs dont explode. It has forever bugged me that I cant find the name of it. If you have any links to videos that would be great too!

Answer 1

It is called "Free Diving"