RCMP say one diver is dead, one has been rescued, and a third is missing near Snake Island, a small, uninhabited, rocky island east of Nanaimo.

Several coast guard vessels, an RCMP boat, a dive team and two aircraft were called to the scene shortly after 4 p.m. PT Friday, said Lt. Paul Pendergast of the Rescue Coordination Centre. At dark, the search for the missing diver was called off.

Search and Rescue Maritime co-ordinator Troy Haddock said the surviving diver was at a depth of 160 feet while the other two were diving at an "extreme depth of 250 feet."

"There were two fellows that were diving together and the report was that they were both in distress," Haddock said.

"One of the fellows had to leave the other one, and the last report was he was on his back, on the bottom."

Haddock said the diver who surfaced went into cardiac arrest, due to decompression sickness.

"When he did hit the surface, he was out of air," Haddock said. "It didn't sound like they were prepared to go to that depth."

It's not known whether the divers got into trouble with their equipment or whether there was a medical emergency.

Officials said the divers were not Nanaimo residents.

There is no further information available at this time.