Hawaiian authorities are investigating a video in which a scuba diver is seen yanking a regulator out of the mouth of another diver who was filming the catching of fish at a reef 50 feet below the surface.

Rene Umberger, who is involved with the Snorkel Bob Foundation, was recording a pair of divers she believed were catching fish for aquariums on May 8 off the coast of Hawaii's Big Island. She was filming the reef to document the effectiveness of certain "fish replenishment areas" when she and other members of the foundation stumbled upon the divers collecting fish.

Suddenly, one of the divers swam over to Umberger and yanked out her regulator, making it impossible for her to breathe. A regulator is a diver's lifeline, delivering oxygen as one part of a scuba set.

Umberger said she managed to get her damaged regulator back in place so she could breathe, and slowly swam back to the surface after the incident.

"When I surfaced at the boat I said, 'oh my God, someone just tried to kill me underwater,'" Umberger said to ABC News' affiliate KITV.

The foundation's director Joan Lloyd told ABC News Umberger would have been facing almost certain death if she wasn't an experienced diver. "She's dived 10,000 times, that's what saved her life," Lloyd said.

Police said that since the incident occurred in the water, it is the jurisdiction of Hawaii's Department of Land and Natural Resources. The DLRN said they are investigating the video, but would not comment on the investigation.

Lloyd told ABC News the foundation fights against the removal of large numbers of specific species of fish from the reefs around Hawaii.

"When you remove certain fish, the coral reef suffocates from algae, and other fish can't survive because it's a symbiotic relationship," Lloyd said. "It's ironic that on the books in Hawaii, we have laws to protect coral, but not to protect fish."