Two Twin Cities men diving in a Wisconsin lake died over the weekend, possibly from decompression illness after surfacing too quickly because one of them had a heart attack.

The Jackson County Sheriff's Office in Wisconsin said Sunday that a 57-year-old man from Eagan was in cardiac arrest when rescuers arrived at the popular Lake Wazee Recreation Area near Black River Falls about 12:15 p.m. Saturday.

The man was being given CPR by two diving companions, including a 60-year-old Minneapolis man who died hours later, apparently from decompression illness despite hours of treatment in a hyperbaric chamber at Hennepin County Medical Center.

The 60-year-old was identified late Sunday as Milton R. Floyd.

Authorities in Jackson County said surfacing too quickly from the lake, the deepest inland lake in Wisconsin, contributed to the deaths. "It certainly was a factor," said Sgt. Mike Johnson, who noted the men were experienced divers diving at between 140 and 200 feet.

Johnson said the department will investigate reports the two men who died might have dived beyond their certification level.

That issue was raised Sunday by Keith Cormican, head of the sheriff's dive team and the owner of a scuba shop, who told KSTP-TV that he knew the men and that they had told him they were certified to 150 feet but that two planned to go to 200 feet.

Johnson said the three were in distress as they surfaced and were helped to shore. He said the heart attack victim was talking when he came out of the water but was in full arrest when rescuers arrived.

Cormican, who said he was familiar with the divers' level of certification, said the same men had decompression problems two years ago when they dove beyond their certified depth.

What came first?

When rescuers arrived, the three men were taken to Black River Memorial Hospital, where the heart attack victim was declared dead.

The other men were airlifted to HCMC for treatment in the hyperbaric chamber, which is used by doctors to increase oxygen levels in bodies.

Although Floyd was placed in the chamber for more than four hours, he died Saturday night. Johnson said the sheriff's office was notified about 7:40 p.m. Saturday of his death.

The third diver, a 53-year-old Minneapolis man, was also treated in the chamber at HCMC and then later released. Johnson said he was the diver closest to the surface when the emergency arose.

Authorities said Sunday that it was still unclear whether the heart attack came first or might have been a result of the decompression illness.

Also unclear was what happened underwater to cause the men to surface so quickly, bypassing decompression stops that allow the body to eliminate deadly nitrogen gas levels that build up in a body the deeper a diver goes.

Dr. Eric Gross, an HCMC physician who works with the hyperbaric chamber, said it is extremely rare for a diver to die from decompression illness. He said about one-half of 1 percent of divers who suffer from decompression illness die.

Gross said the heart attack might or might not have been related to the decompression illness, which can cause such things as rash, joint pain and paralysis.

"Fatalities are rare," he said Sunday. "Most of the time with decompression illness you are going to see pain. We haven't had a death from this in I don't know how long."

Lake Wazee is one of the premier deep-water diving spots in the Midwest because of its clarity and depth. According to his blog, Floyd's favorite diving site was Lake Wazee, where he dove last month with friends. In the blog he notes that he and others had dived to about 180 feet at least once at Lake Wazee and had gone beyond 150 feet on other occasions.

Johnson said the lake has depths of about 350 feet and is a popular destination for divers from all over the Midwest.

"It is not unusual for people to come from all over the U.S. to dive there," said Nathan Smrekar of Minneapolis, who grew up near Lake Wazee and has seen numerous divers there while snorkeling and fishing. "It is exceptional. The water quality makes it ideal."

Because of its depth, Lake Wazee is used by law enforcement for training, said Smrekar, who said he spent many weekends there while growing up.

Because it's so deep, the lake is considered dangerous. Numerous signs warn divers that the nearest hyperbaric chamber is three hours away in Minneapolis.

"The signs are everywhere," Smrekar said, "you can't miss them."

Emergency on dive?

Gross said experienced divers normally would not experience decompression illness unless they lose track of their depth or the time they have been down.

About the only thing that causes experienced divers to come up and disregard decompression stops, Gross said, is if there is a life-threatening emergency on the dive.

"I think it's a safe bet that either these divers shouldn't have attempted these depths," Smrekar said, "or events underwater led to an emergency resurfacing, causing decompression sickness."

Heron Marquez Estrada • 612-673-4280