This horrifying video was taken by a scuba diver in Hawaii who was attacked underwater by another scuba diver who ripped off her oxygen supply.

Rene Umberger, an environmentalist, was diving with several other anti-aquarium trade activists when they spotted two other divers who were collecting fish in a reef. Those divers apparently didn't appreciate having their pictures taken, so one of them swam over to Umberger and pulled the oxygen regulator out of her mouth. Luckily she didn't panic and was able to recover quickly and get her oxygen back in. But she says another inexperienced diver wouldn't have known what to do and would have likely died. The entire incident was caught on video and Umberger hopes the other diver will be arrested.