Somewhere beyond the earth yellows and sandy browns that stretch into infinity in Sinai, its prodigious coppery mountains tower over the vast blues of the Red Sea. Along the southeast coast sits the town of Dahab (Arabic for 'gold') in all its understated glory; a hippie commune, a diver's Mecca, a bastion of bohemia, and a backpacker's paradise. The real gold, however, is found in the town's otherworldly pristine landscapes, imploring you to believe in great things.

Beneath the surface of Dahab's serene sapphire waters, the sea remains true to its treacherous nature. Many venture to these inhospitable depths, defying their own human limitations for a few moments of respite from all the mundane banalities that constitute the bane of our existence.

Two such adventurers were Irish technical divers Conor O'Regan and Martin Gara. The deep came calling before either turned 25. Their bodies were found locked in an embrace 102 metres deep into Dahab's infamous Blue Hole.

Their bodies were found locked in an embrace 102 metres deep into Dahab's infamous Blue Hole.

Tarek Omar still remembers it like it was yesterday – his first of many 'missions', as he likes to refer to those dives for which the purpose is to recover the dead bodies of fellow divers. 'The Elder Diver', as he has come to be known, has dived the Blue Hole for almost 20 years, even emerging with a title, one time, after a record-breaking 209-metre dive. "I know it like my kitchen," he says casually between sips of Bedouin tea.

It is said that over 150 divers have lost their lives in Dahab's Blue Hole - often considered the most dangerous diving site in the world - in the last 10 years, earning the submarine sinkhole the ominous moniker 'Divers' Cemetery'. You can see their names inscribed on commemorative plaques embedded in a mountain front by the deadly dive site.

Omar has lost count of the bodies he has recovered from the seafloor. A technical diving instructor by profession, there are times when he dreadfully puts his diving suit on, preoccupied by his looming encounter with the ghosts of the abyss. He plunges into the bottom of the aquatic graveyard, scans it with his eyes, and follows whatever clues they might have left behind until he locates the decaying human remains – that's half the job. The other half is to ascend, facing the body. "Recovering bodies is a case by case thing; I do it pro bono," he says. "It is a very critical and difficult thing to do – it requires more than just being a technical diver, it takes more than experience. It is very hard because you dive deep and you stay down to locate the remains."

It is said that over 150 divers have lost their lives in Dahab's Blue Hole - often considered the most dangerous diving site in the world - in the last 10 years, earning the submarine sinkhole the ominous moniker 'Divers' Cemetery'.

Underwater recovery can very easily go wrong. A diver must form an idea of where the body may have sunk before even getting into the water, considering factors such as weight (how much lead they had strapped to their suit), and where they were last spotted by their [dive] buddy.

Legendary Australian diver Dave Shaw died shortly after a record-setting 270-metre-deep dive into a South African cave while attempting to recover the human remains of another cave diver. Omar is aware of the dangers but, at 51, he still maintains a fresh take on things, balancing out the risk of dying and the benefit of helping out. "Life is risk; anything can happen, even in the safety of your own home. Tech diving is all about calculating those risks and leaving nothing to chance," he resigns. "You do your best before you get in; it's a military discipline – you make a plan and execute it, and that's your best, that's what brings you back. There's a plan for everything: stress management, contingencies, everything. You have to be disciplined; you have to stick to the plan, stick to the schedule."

Tech diving is basically a diver depending entirely on his or her self and their knowledge underwater, because diving is science. It's not like recreational diving where it can be a spur of the moment thing, it has to be planned.

Local legend has it that the Blue Hole is haunted by the ghost of a girl who was made to drown herself there; it is she, some believe, who lures these divers to their untimely deaths. Having explored those bottomless depths countless times, Omar is all too familiar with the ghost stories. "I grew up listening to these stories, so I became curious and wanted to explore," he recounts. "That's why I became a tech diver, to explore the Blue Hole."

One ghost that has latched itself onto him, however, is that of Russian-Israeli diver and diving instructor Yuri Lipski, whose body he recovered at the request of his bereaved mother. "It was exceptionally hard for me because I had met Yuri twice before. He was very reckless," he reminisces. Omar had warned Lipski against attempting the dive, but to no avail.

Omar's inability to prevent Lipski's death is not the only thing that haunts his dreams; Lipski wore a helmet camera to document the dive – the footage would become the Elder Diver's biggest regret.

"Two days after we recovered his remains and gave [his mother] his belongings and equipment, she came to me asking that I help her disassemble them so she can pack them. The camera should have been damaged or even broken altogether because I had found it at a depth of 115 metres, and it is only designed to sustain 75 metres; but, to my surprise, the camera was still working. We played it and his mother was there. I regret that his mother will have this forever," he said ruefully. "If I had known the footage existed I'd have flooded it. I think the thing that really upset and saddened me about it was that his mom has it now – she has the footage of her own son drowning."

If I had known the footage existed I'd have flooded it. [...] his mom has it now – she has the footage of her own son drowning.

Historically employed in underwater warfare, technical or tech diving is a diving method that requires a great deal of preparedness, vigilance, planning, and exactitude to survive the perilous aquatic journey that can take divers to depths of well over 40 metres, which is the depth limit set for recreational scuba diving. "Tech diving is basically a diver depending entirely on his or her self and their knowledge underwater, because diving is science. It's not like recreational diving where it can be a spur of the moment thing, it has to be planned," he says.

Being a member of the exclusive 200-metre club – it is said that fewer people have dived to depths of over 200 metres than those who have landed on the moon – Omar is one of Egypt's and the world's foremost technical divers.

Being a member of the exclusive 200-metre club – it is said that fewer people have dived to depths of over 200 metres than those who have landed on the moon – Omar is one of Egypt's and the world's foremost technical divers. "I became a diver because I live here in Sinai and the best activity is the sea; then, when I got into diving, I wanted to specialise in tech diving because it wasn't very common in Egypt at the time. That was back in 1994," he relates. "There weren't any reputable tech dive centres [in Egypt] because no one wanted to take a chance. I was the first to open one in 1991: Tek Tribe. Tech diving was first introduced in Egypt in 1995, but it became more popular when we set up Tek Tribe."

Despite having been demilitarised in the 60s, technical diving is still considered an extreme sport and so is cave diving. To dive the Blue Hole you need to master both. An 80-metre-wide and almost 100-metre-deep opening in the reef, the Blue Hole is on every diver's bucket list. Its crystal clear and minimal undertow waters, which allow for good visibility even at great depths, make for optimal diving conditions. At 52 metres, a ray of light slithers the water – that's how you know you have arrived at the downward tunnel leading to the open water, known as The Arch. The same daunting route is not attempted by recreational divers who only ascend and descend the Blue Hole vertically within their depth limits.

Uncertified divers are not allowed into the Blue Hole, and even certified ones are required to follow a guide, yet these laws are not always observed.

Many technical divers approach the compound dive with criminal levity. "There are no supernatural reasons behind [the fatality rate], the reason is often the diver," Omar says matter-of-factly. "The Blue Hole is the most wonderful dive. If I told you this street has a ghost, you will always fear; people dive in a state of mind that's not exactly top notch – some are unqualified and inexperienced. About 30 to 40 percent of the time, it is psychological; with the slightest problem underwater, the situation explodes."

...with the slightest problem underwater, the situation explodes.

The culprit is often the diving gear; at a depth below 30 metres, compressed air becomes toxic, which causes nitrogen narcosis or the martini effect – a state similar to drunkenness that intensifies with depth – which impairs the diver's judgment. It has also been found to induce overconfidence, hallucinations, and euphoria, often luring them to greater depths than their air supply permits. Lipski, and many others, attempted the dive on one tank of air. "Compressed air is not suitable for technical diving; in dives like these, we use Trimix [a combination of oxygen, nitrogen, and helium] because it minimizes the martini effect," Omar explains. "It's expensive, but it is the only thing we can inhale underwater."

Other times, it is the lack of preparation and planning that kills divers. "They should know how much air they consume on land and how much they'll be consuming down there, because a minute's worth of air makes a world of difference," he urges. "They need to know how much they consume and account for water pressure, have reserves, but many people just follow their computers under the water. Ignorance kills them; they need to understand that once they go beyond 40 metres deep, they're stepping into a situation that requires them to be alert."

The ocean squeezes you, you can actually hear it if you go in a submarine. It sounds romantic but it's actually very dangerous.

A diver must not only consider their bottom, ascent, and descent time, they must also account for deco (short for decompression) stops, which are necessary for their bodies to adapt to the decreased pressure, otherwise the gasses dissolved into the bloodstream form bubbles causing decompression sickness (or the bends), which can be fatal if not treated immediately.

All facts, figures, technicalities, and scientific explanations aside, Omar knows the real killer of these men and women: their aspirations to push the boundaries of human limitations. Even he has had his brushes with self-glory. "When I'm down there, I feel special; I know that only a select few people have been there, it's not accessible to many," he says passionately. "The ocean squeezes you, you can actually hear it if you go in a submarine. It sounds romantic but it's actually very dangerous."

It is believed that, to summon sirens, you need to lie still at the bottom of the ocean; it is only when your heart is about to give in that they will come and take you to their realm. These adventurers have come from all corners of the globe to brave the bottomless depths, but they had billions of years' worth of condensed water flowing against them. Yet, many would tell you they would take the Divers' Cemetery as their final resting place over their family plots any day of the week and twice on Sunday.

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