O.C. Diver Spears Big Fish Off Baja, Vanishes : Disappearance: Companions say he failed to swim back to boat after spearing a 100- to 125-pound grouper.

A skin diver from Rancho Santa Margarita was presumed dead Wednesday after he failed to surface from a deep-water dive off La Paz in Baja California.

Kent McIntyre, a 30-year-old chiropractor and the father of two, was on a four-day trip with three companions, all members of the Long Beach Neptunes. The Neptunes are world-class “free divers,” spear fishermen who do not use scuba tanks but hunt with only a mask, fins, snorkels and spear guns.

The group included, Allan Drexl, 41, a Glendale optometrist; Doug Ulmer, 47, a dermatologist from Long Beach; Robert Strohbach, a Fontana chiropractor, and McIntyre. They had chartered a 46-foot boat and were anchored off a group of remote islands in the Sea of Cortez when McIntyre failed to return to the vessel.

Mexican coast guard officials in La Paz said that the divers filed a missing person’s report and that the body has not been found, said Martin Torres, a spokesman with the Mexican Consulate office in Los Angeles.

The accident occurred while the divers, including McIntyre, were hunting for groupers. Unlike scuba divers, who employ a buddy system, free divers go as a group but essentially hunt alone. There is an unwritten rule, however, that after a diver spears a large fish he should seek another diver to monitor him as he retrieves the catch, said several experienced free divers.

When the group last saw McIntyre he had just told Ulmer, “There are some big groupers down there. But they’re real deep.”

“And that’s the last he said to him,” Drexl recalled.

The four were diving along an island where the ocean drops off, and “it gets deep very fast,” Drexl said.

At the time, Strohbach had speared a 25-pound grouper, and Drexl swam over to him to help lift the fish into a small boat, called a panga. They were about half a mile from the main boat and a quarter of a mile from McIntyre.

“We put the fish into the panga and started to swim toward the main boat when I noticed Kent’s float about a quarter of a mile from us,” Drexl said.

The float, Drexl explained, is on 100 feet of line attached to the spear and used to mark a fish’s location once it is shot.

Because of the size of their powerful prey, sometimes several hundred pounds, it could be disastrous for a diver holding a spear gun to remain attached to one of these ocean giants.

“They’re so big you can’t control them,” Drexl explained.

As Drexl approached McIntyre’s float he had two thoughts--that McIntyre had become entangled with the line, or that he had swum back to the boat.

“I swam down, and when I swam down to the bottom the fish was there and no Kent. All you can see was a spear shaft in this tiny hole and this fish was 100 to 125 pounds. I grabbed the shaft and I gave it a couple of yanks, then I had to go up because it was deep. Once I got up to the panga, Kent wasn’t there. My only hope was that he was on the boat, which he wasn’t.”

At first they searched for two hours and found nothing, then were joined by half a dozen other divers who heard their plea for help over the boat’s radio. Ten hours later they ended the search.

Drexl said they were able to recover McIntyre’s spear gun about a quarter of a mile from an island. It offered no clues.

“We are 100% sure that he died,” said Strohbach, McIntyre’s best friend.

Strohbach said they headed into La Paz, where they reported the incident to port officials.

All four were experienced divers, and Drexl, Strohbach and McIntyre had dived together “hundreds of times,” Drexl said.

The men believe that McIntyre suffered a shallow-water blackout, said Wes Morrissey, president of the Long Beach Neptunes. Last year, he said, three members experienced shallow-water blackouts on dives, but all were brought to the surface by someone nearby and revived.

“Lots of deep divers overextend on their way up, and because of the changing pressure, it creates a gas imbalance. It’s not the bends, because that is with nitrogen and scuba tanks. Here, as you ascend the oxygen is depleted in your brain. The ascent creates a vacuum and acts in combination with imbalance of the gases in your system and partial pressures,” said Morrissey.

“We do feel a great sense of loss,” Morrissey added, “and we send out our condolences to his family.”