“Horrified at watching his friend die in front of him, Gronqvist nevertheless had to steady himself and breathe calmly to avoid the same fate.”

The group were split into a lead pair of Patrik Gronqvist and Jari Huotarinen with the other three, Vesa Rantanen, Jari Uusimaki and Kai Kankanen, following about two hours behind. They had planned for the trip – including the lengthy decompression stops needed to ascend from such depths – to take around five hours. But 11 nightmarish hours later Kai Kankanen, the last diver to surface, was only just climbing out of the frozen water. Rantanen was suffering badly from decompression sickness and Jari Huotarinen and Jari Uusimaki were dead.

What’s incredible about this story is not just that the three remaining divers survived – although that was an achievement in itself. All three had spent extra time at depth trying to help their friends and faced a horrifying choice between running out of air or contracting the bends by coming up too quickly. Yet they successfully walked that tightrope, calculating the timings as best they could and staying alive. All the while staying calm enough to avoid succumbing to hypercapnia themselves.

No, the truly incredible element of the story is that the team, aided by other friends, went back into the cave just over a month later and managed to bring back the dead bodies of their two friends. The tale of this recovery mission is told in the documentary Diving Into the Unknown, released earlier this year.

The film reveals that the meticulously-planned recovery operation had to be kept secret. The Norwegian police had deemed the attempt too dangerous, and the team were in fact arrested when they’d finished (although they were later released without charge). But the film also shows the risks they took, and the lengths these courageous Finns would go to to ensure that “no-one was left behind”.

The Woman Who Came Back From the Dead

Perhaps slightly less extreme than the incident in the Plura caves, but no less horrifying for those involved, is the tale of Hilary Greenberg, a woman who seemingly came back from the dead after spending about 40 minutes without a discernible pulse.

Doctors and diving enthusiasts Bill and Hilary Greenberg were on holiday with their three young sons in Costa Rica when the accident happened. That morning, the boys – aged 11, 13 and 15 at the time – had headed off with an instructor while Bill and Hilary joined a more advanced dive party. With years of diving experience between them, the couple were two of the best qualified members of the group.

On their second dive of the day however, something unexpected happened. An underwater ‘surge’ or strong current hit them, pushing them forwards by about 40 foot along the edge of a reef. Except that Hilary wasn’t carried with the rest of the group. Four anxious minutes passed while Bill and the divemaster leading the party searched for her. Eventually Bill spotted his wife lying on the seafloor with her regulator out of her mouth – Hilary had apparently been knocked against the coral and it had fallen out. She was unconscious and wasn’t breathing.

Raising the Dead

Diving partners Don Shirley and Dave Shaw were part of an elite club in scuba diving. In the history of the sport, fewer than 30 people have ever reached depths of more than 250 metres with self contained underwater breathing aparatus. Even fewer have lived to tell the tale.

To come up from that kind of extreme depth requires carefully-timed decompression stops at specific depths in order to avoid the buildup of nitrogen which causes the bends. The process takes hours, with every minute at the bottom adding to the time you need to spend in the water on your way up.

In October 2004, with Don Shirley acting as his dive partner, Dave Shaw descended to the dizzying depth of 271 metres below the surface in a cave called Bushman’s Hole in South Africa. In the process he set several records which still stand to this day, including the deepest ever reached using rebreather apparatus.

“Fewer than 30 people have ever reached depths of more than 250 metres with scuba gear. Even fewer have lived to tell the tale.”

Although more complex than conventional ‘open circuit’ scuba equipment, rebreathers are more efficient, allowing divers to spend longer at depth while carrying less gas with them. Dave had been able not only to make it almost to the bottom of the hole, but to spend some time exploring. While he looked around however, he found something unexpected – the skeletal body of Deon Dreyer, a young diver who had died further up in the cave some 10 years before.

Shaw was unable to free the trapped body on that first dive. But hoping to bring some closure to Dreyer’s family, he and Shirley planned to return the following year on a recovery mission. In January 2005, with a careful plan, a backup team of nine experienced cave divers and a mobile decompression unit on the surface in case of emergencies, Shaw and Shirley went into Bushman’s Hole again.

The plan was for Shaw to descend to 270 metres and follow the line which he had tied to Dreyer’s body on the previous dive. He’d have a few minutes at the bottom to free the corpse and slip it into a specially designed body bag which would get passed back up the line of support divers, starting with Shirley, who would be waiting for his friend at 220 metres.

The body, according to the plan, would be raised about 80 minutes after the start of the dive, but in order to stay alive himself, Shaw would need to spend around 12 hours in the water decompressing as he came up.

In the event, nothing went according to plan. Video footage from his head-mounted camera showed Shaw descending quickly, reaching the body fine. But as he battled to get it into the bag, it started floating free. As he struggled to get the body in the bag, his breath quickened leaving dangerous amounts of carbon dioxide in his lungs.

Shaw would have been feeling disorientated and confused – as the contemporary account in Outside Magazine put it: “It was probably as if he had downed four or five martinis”. When he finally gave up battling with the body and turned to leave, Shaw’s torch became entangled in the dive line, trapping him. He reached for his diving shears to cut it but he was too late and he succumbed. By the time Shirley, who was 13 minutes behind Shaw, was 50 metres into his dive, his friend was already dead.

The full story of the dive, told in Phillip Finch’s book Diving Into Darkness, reveals an interesting postscript to Shirley’s incredible tale of survival. Four days later when divers were recovering the last bits of gear from the cave, they were surprised to discover that Dave Shaw’s body had floated up to just 20 feet below the surface. He was still attached to the line he’d become entangled in, the other end of which was tied around the body of Deon Dreyer. Shaw had died in the attempt, but he’d achieved what he and Shirley set out to do – to bring Deon’s body home.