Competitive freediving is a sport in which humans hold their breath and see how deep they can swim.

And when they do, strange things can happen, including losing color vision and becoming “drunk” off the nitrogen in the body.

While archaeological evidence suggests that freediving may date to the Stone Age, it seems to enter public conversation for just two reasons, professional freediver Martin Stepanek told Business Insider: when someone breaks a world record or when someone dies…

Read the full story at Business Insider.