Blue Hole (Red Sea)
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The Blue Hole is a submarine sinkhole, with a maximum depth within the hole of just over 100 m (328 feet). There is a shallow opening to the sea around 6 m (20 feet) deep, known as "the saddle", and a 26 m (85 feet) long tunnel, known as "the arch", whose top is at a depth of 55 m (181 feet), and whose bottom falls away as it reaches the seaward side to about 120 m (394 feet). On the seaward side the depth drops steeply to over a thousand metres (3500 feet) deep. The hole and the surrounding area have an abundance of coral and reef fish. The Blue Hole is a hot spot for freediving because of the depth directly accessible from shore and the lack of current.
The Blue Hole at Dahab is believed to be the deadliest dive site in the world, with some suggesting it to have claimed the lives of 130 to 200 divers in recent years. The reasons why this site is the most dangerous in the world are not clearly understood, with differing explanations given for its high death rate.
The Blue Hole was historically avoided by Bedouin tribes people who inhabited the area. There was a local Bedouin legend that the Blue Hole is cursed by the ghost of a girl who drowned herself there to escape from an arranged marriage.
However, the Sinai Peninsula was occupied by Israel during the Six-Day War of 1967 (with Israel occupying the territory until 1982). The first people to dive the hole with modern scuba diving equipment were Israeli divers led by Alex Shell, who noticed the underwater arch in 1968. By the time Israel handed the Sinai Peninsula back to Egypt in 1982, the Blue Hole had developed a reputation as a diving site amongst the international scuba diving community.
The Blue Hole is dived almost every day by recreational divers. Local dive centres take divers who are qualified to dive to 30 m (AOW level or CMAS**) to do the site known as El Bells or Bells to Blue Hole. The entry is from the shore further along from the Blue Hole at an entry called The Bells. At 26 m at the bottom of the Bells is a mini arch that should not be confused with the arch in the Blue Hole itself. The dive is then a wall dive that finishes crossing the Blue Hole saddle at a depth of 7 m. Recreational divers do not get to see the Blue Hole arch when doing the Bells to Blue Hole dive.
However, the Blue Hole is notorious for the number of diving fatalities that have occurred in the past. One local Tech-Diver puts the number of deaths over 130-200, and thus claims that it is the most deadly dive site in the world.
Accidents happened as divers tried to find the tunnel through the reef (known as "The Arch") connecting the Blue Hole and open water at about 52 m (170 feet) depth. This is beyond most recreational diving limits and the effect of nitrogen narcosis may be significant at this depth for some. Divers who missed the tunnel sometimes continued descending, hoping to find the tunnel farther down and became increasingly narcosed; furthermore, the rate of consumption of air by an open-circuit diver increases the deeper the diver descends.
The "Arch" is reportedly  extremely deceptive in several ways:
- It is difficult to detect because of the odd angle between the arch, open water, and the hole itself.
- Because of the dim lighting, most light entering from outside through the arch and lack of reference points, it appears shorter than it really is. Divers report that the Arch appears less than 10 m long but measurements have shown it is 26 m long from one end to the other.
- There is frequently a current flowing inward through the arch towards the Blue Hole, increasing the time it takes to swim through.
- The arch continues downward to the seabed, which is beyond view and there is therefore no "reference" from below.
- In the very clear Red Sea water, the arch may seem to be nearer and smaller than it is.
- The diver's mind may be muddled by nitrogen narcosis.
Divers who resist the temptation of the Arch and remain within their training and limitations are in no more danger than on any other Red Sea dive site. However, the Arch has proved irresistible for many and thus the dive site is considered unsuitable for beginners and a potential trap for even experienced divers. The Egyptian Chamber For Diving & Watersports (CDWS) now has a policeman stationed at the Blue Hole to ensure divers are diving with a certified guide who will make sure safety procedures are followed.
At 55 m the depth itself is not particlarly challenging to suitably qualified divers and is almost not a technical dive. The challenge is gas management as any lingering or errors at this depth, plus negotiation of the horizontal section, will need more than a single tank of breathing gas to do safely. Diving through the arch requires suitable training and equipment but gas mixtures such as Heliox or Trimix are not required or may even be undesirable. It can be done on air if a PPO2 of 1.6 (MOD66m) is accepted or on 18% O2 if maintaining a PPO2 of 1.4. However, it does require careful gas planning as diving it on a single tank is marginal and at least one stage tank is required. A stage of a suitable Nitrox mix may assist decompression if managed correctly but is not essential. Divers should be familiar with, and comfortable with, their personal nitrogen narcosis susceptibility at this depth.
The number of diver deaths in the Blue Hole is not known, one source suggests 130 in the last fifteen years.  The majority of those killed were experienced, including highly trained technical divers and diving instructors. There have also been snorkelling deaths at the surface unrelated to the depth of the hole.
A notable death was that of Yuri Lipski, a 22-year-old Russian-Israeli diving instructor on 28 April 2000 at a depth of 115 metres after an uncontrolled descent.   Yuri carried a video camera, which filmed his death. This has made it the best known death at the site and one of the best known diving deaths in the world. The video shows Yuri in an involuntary and uncontrolled descent, eventually landing on the sea floor at 115 metres where he panics, removes his regulator and tries to fill his buoyancy compensator but is unable to rise. At 115 m he would have been subject to severe nitrogen narcosis, which may have impaired his judgement, induced hallucinations and caused panic and confusion. Lipski had a single tank assumed to be air.
Lipski's body was recovered the following day by Tarek Omar, one of the world's foremost deep-water divers, at the request of Lipski's mother. Omar had earlier twice warned Lipski against attempting the dive. On the bottom, Omar found Lipski's helmet camera, still intact. The video it contained is available on YouTube, entitled "Fatal Diving Accident Caught On Tape". Omar says:
|“||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... 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.||”|
|— Tarek Omar, |
Documentaries about diver deaths at the Blue Hole
Two television documentaries have been produced about diver deaths at the Blue Hole, investigating the video of the death of Yuri Lipski:
- Sacred Truth, The Blue Hole of Dahab (2004), by Elena Konstantinou and Svetlana Klenova, NTV (Russia)
- Monty Halls and the Divers' Graveyard (2013), by Monty Halls, Channel 5 (UK)
- "The Arch at Blue Hole: Personal experience on diving and guiding at the Blue Hole".
- "Blue hole maps". Archived from the original on March 21, 2008.
- Grossekathöfer, Maik (July 13, 2012). "A Visit to the World's Deadliest Dive Site". Spiegel Online. Retrieved August 27, 2017.
- Top diver’s death casts long shadow over deep beauty of the Blue Hole Edmund Bower, Sunday 27 August 2017, The Guardian
- Monty Halls and the Divers' Graveyard, Channel 5 (UK) television, 9pm to 10pm, Monday 2 December 2013
- "The Bells dive site: Diving from The Bells to Dahab Blue Hole".
- FATAL ATTRACTION Theodora Sutcliffe
- Ghoneim, Niveen (October 20, 2016). "Egyptian Diver Tarek Omar: The Keeper of Dahab's Divers' Cemetery". Cairo Scene. Retrieved August 27, 2017.
- Bower, Edmund (August 27, 2017). "Top diver's death casts long shadow over deep beauty of the Blue Hole". The Guardian. Retrieved August 27, 2017.
- An Elena Konstantinou film “Sacred Truth” aka “Blue Hole” Documentary by Elena Konstantinou (Vimeo), produced for NTV Russia
- Graphic: The Blue Hole in the Gulf of Aqaba. Diagram showing location of the arch, at Spiegel Online.