Dog Days in Dahab
What is it about the Blue Hole that lures so many divers to their deaths If it were simply divers going too deep on air, wouldnt there be a similar death toll all over the Sinai Peninsula Intrigued, Louise Trewavas decided to take a small team to dive, measure and explore the site

DAHAB TODAY IS WHERE SHARM EL SHEIKH was 15 years or so ago, before the Blairs and the bucket-and-spade brigade arrived. Its a laid-back, slightly quirky Egyptian town, with an economy that runs on diving and an unusually large population of cats and dogs, fed by indulgent Europeans.
     Dahab has that elusive quality: ambience. Its also the portal to the Blue Hole, the worlds most dangerous dive site.
     The number of Blue Hole fatalities is hard to come by. The Egyptian authorities are coy about the current death toll.
     Initially I had been told that 48 divers had lost their lives. Harry Hayward from Deeper Blue Divers, who looked after the logistics of the project, said it was more like 70. In the peak season we were losing a diver a month, he commented. A veteran dive guide from Planet Divers said he had seen a list of the dead three years ago with more than 100 names on it.

the Blue Hole
     The site is north of Dahab, a 40 minute bumpy 4x4 ride along a coastal desert track. The seemingly bottomless coral lagoon attracts truckloads of day-trippers, some to dive, some to snorkel, many simply to hang out at the Bedouin-style cafŽs. Equipped with drysuits, rebreathers, twinsets, stage cylinders, and survey paraphernalia, our team looks frightfully overdressed next to the clusters of swim-suited snorkellers.
     The dive team consists of Liz McTernan, Nick Barron, Mark Brill (video), Tracie Cameron (stills) and me. I stagger through the knee-deep water to the entry point and attempt to put my fins on without tipping headfirst off the tiny, submerged wooden platform.
     Descending the steep coral drop-off, I make my way to the eastern side of the lagoon. The opposite wall seems to close in on me, and a dim blue glow becomes visible ahead at about 50m.
     I reach the arch, a massive opening in the coral wall with a roof at 55m and jagged sides that drop away to more than 100m. This is the challenge that has intrigued and endangered so many: the promise of a spectacular dive through the arch and out into the open sea.
     My depth gauge is reading 60m as I cruise into the arch, scattering clouds of tiny fish before me. As I swim further, I dont seem to be getting anywhere. What had initially appeared to be an opening is actually a tunnel.
     Underwater distances are difficult to judge at the best of times, but with the bright blue of the outside sea making the tunnel into a dark silhouette, the outside appears very close. Im still swimming, and Im only halfway through the arch. I pick up my rebreather handsets and it is too dark to read the numbers.
     Looking down into the black I can see no sign of the seabed. Hanging there under the arch, in the middle of nothingness, I shudder at the thought of so many divers dying in this spooky and bewitching place. This is no place for anyone who is not 100% in control of their buoyancy.
     I am breathing 50% helium, and my level of narcosis is equivalent to less than 25m, but I still feel overwhelmed by the scale and drama of the site.
     Back on dry land I ask several of the dive guides about the distance through the arch to the sea. About 12m, says one, maybe 13. It only takes a couple of minutes to swim through it.
     We measured it on a later dive. Its 26m - the equivalent of swimming the length of an average swimming pool. It seems that no matter how many times you dive here, its difficult to get a grip on the reality of this site.

the survey
After our introduction to the seductive depths of the arch, we begin the survey work. The strategy is two-part, to take a series of key measurements, noting distance, direction and depth; and to set up buoyed survey lines, giving us fixed points to take horizontal, 360 slices of measurements at a series of depths. The aim is to use this information to produce an accurate 3D map of the site.
     I follow the reef down to a deep gully that runs along the centre of the lagoon and under the arch. The seabed at the far end of this narrow passage rises to 60m, and I send up an SMB and search for a suitable tie-on.
     I pick up the DiveRay sonar gun clipped to my harness. Mark has cable-tied a Suunto liquid-filled compass to the top and this allows me to take readings of the distance from the survey line to the walls of the lagoon at every 15.
     The floating face of the compass acts as a spirit level, enabling me to shoot straight with the sonar gun.
     We have pre-printed slates to help us record the information at a series of depths. Its a dizzy job; spinning around, taking aim and writing down a string of numbers. Its easy to clock up a lot of deco time, but this gives us more opportunity to explore and measure the shallower sections of the lagoon.
     We dive on average for 90 minutes each day, starting deep and ascending, taking as many measurements as we can get. Photos and video footage help us record and interpret the data.
     The plan for today is a deep exploration dive on the outer reef to a maximum of 105m, swimming back through the arch from the open sea and into the lagoon.
     Different divers have given us wildly varying accounts of the conditions well find, and the only way to discover the truth is to explore it ourselves.

falling into the blue
We surface-swim out over the saddle - the eroded lip of the lagoon that dips to about 7m - and onto the outer reef. Using the marker buoy to identify the position of the arch, I start the descent slightly to the south of the arch.
     The outer reef is thriving, far prettier than the inside of the lagoon. It forms a sheer drop-off that bulges out slightly and then falls inwards, leaving me hanging over nothingness. The visibility is seemingly limitless, and when I spin around and look out into the sea I feel as if I can see for miles. When I look down, the deepening blue is seductive and gorgeous. I fall into it.
     At 80m the whole world has turned blue; I can see the bottom of the reef wall and the seabed sloping away from it. Still dropping, I turn on my torch and look around for the others.
     I stop at 102m and start noting my surroundings. I know Im next to the arch, but I cant make it out until I swim around a corner of the reef.
     To my surprise, the seabed under the arch is a simple continuation of the sandy gully. From above, it had seemed darker and steeper, but it was simply the area of shadow beneath the arch that appeared to make it black.
     I can see the entire structure of the lagoon - it slopes down and towards me in a cone shape with a flattened bottom. The arch is a towering, tunnel-shaped door on one side of the cone, pouring sand out of the gully and away down the sloping seabed. Looking in through the arch is like being given a snapshot of the entire site. This is the first time I have been able to comprehend it fully.
     Attempting this dive on a single cylinder of air is what has killed and bent a very large number of divers. It is beyond the recommended depth for an air dive, it is an overhead environment and there is effectively no bottom. The macho reputation of the site has lured many divers to risk their lives unnecessarily.
     While the arch is a dramatic dive, its not worth dying or bending yourself for.
     The team found many illusory features of the site. The arch is not straightforward to find - its at an angle to the surrounding reef. The light coming through it can be dim, but once you focus on it, the arch appears to be a silhouette when its actually a 26m long, 25m wide tunnel. Its easy to get a bit lost and disorientated, which will cost you lots of gas and decompression time.
     We had good visibility and no noticeable current, but visibility can get murky, and divers have reported strong downwards currents on the outside wall.
     You might find yourself swimming against a current while trying to get through the arch - all the more reason to take plenty of gas.
     If you want to do the dive, get technically qualified, and use a twinset of trimix - that way you can take your time and appreciate it safely, with a clear head. Dahab-based Deeper Blue Divers, Poseidon, Orca and Planet Divers dive centres all offer technical training.
     Dahab is famous for fantastic, easy-access, scenic shore dives from 10-60m. Its not necessary to dive deep to enjoy what Dahab has to offer, but if you cant resist the challenge, make sure you go properly equipped and gassed up, take a torch and use a reputable dive centre.
     The map we produced is freely available on, giving divers hard information about what they are getting into.

These frames from Mark Brills video give an idea of the view from the Blue Hole as a diver passes under the arch - the open sea appears deceptively close
Liz McTernan takes survey notes
Liz with the underwater sonar
The project team consisted of Mike Tomlinson, Tracie Cameron, Madeleine Westwood,Nick Barron, Liz McTernan, Harry Hayward, Louise Trewavas and Mark Brill.

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