Its exceptional water clarity and a beautiful underwater arched tunnel makes the Dahab Blue Hole very tempting.
The Dahab Blue Hole is a vertical cavern (sink hole) that is about 130m deep. Located about 10Km north of Dahab in the Red Sea. It is considered one of the most famous dive sites in the world and is visited by thousands each year.
However, the Dahab Blue hole is also nicknamed the ” divers cemetery”. It is reported to have claimed as many as 200 divers over recent years.
That being said, it is actually a nice and easy dive site as a shallow dive. However, quite treacherous for curious/adventurous divers that are unprepared for its depths that can be quite deceiving.
Most divers claimed by the blue hole were attempting to dive under the blue hole’s arch. There is a beautiful cathedral like 50m arch underwater arch that reveals a 26m long tunnel directly to the Red Sea through the seawall. The combination of the water’s clarity and the ability to see all the way through the tunnel makes it very alluring.
However, at these depths, unprepared divers are subject to disorientation and/or hallucinations caused by nitrogen narcosis. It is for this reason that many never make it back to the surface. Furthermore, it is often overlooked that this is really a two tank dive. This dive is just doable as a single tank. Therefore its advisable to use two tanks for possible mitigating factors such as currents and underwater delays of any type.
Watch the following video for more details.
Below are some of the primary reasons for the high accident rate at the Dahab Blue Hole:
– Notoriety of the site attracts divers and presents a challenge that tempts many who lack the necessary competence.
– Accessibility of the site and the clear, warm waters of the Red Sea makes the dive look more benign than it is. At over 55 m, and with an overhead environment, the dive requires competence usually associated with moderately advanced technical certification, with a technical extended range (55 meters on air) or Tech 60 (normoxic trimix) as a minimum qualification.
– The entry to the Arch is not easy to find because of the indirect line between the Blue Hole and open water. Divers who miss the entry may inadvertently continue to descend past it, while the floor continues on down to well over 100 m providing no visual depth reference.
– Time taken to pass through the Arch may be underestimated. The tunnel appears shorter than it actually is because of the clarity of the water, the light at the outside end and the lack of reference points; divers report that the tunnel appears to be less than 10 m long but has been measured as 26 m. Moreover, there is frequently a current flowing inward through the arch into the Blue Hole, increasing the time it takes to swim through and increasing gas consumption.
– Depth and the time taken to find and navigate the tunnel inevitably makes this a decompression dive requiring decompression stops on ascent in order to avoid decompression sickness (DCS). Also, the rate of diving gas consumption increases with depth and effort, which can lead to divers running out of gas or beginning the ascent with insufficient gas to make the decompression stops required.
– The likelihood of nitrogen narcosis causing confusion leading to poor judgement in an already demanding situation is significant at this depth. Although the effects of nitrogen narcosis may be mitigated by using trimix or heliox the Arch is insufficiently deep to make its use obligatory.
– Temptation to dive on a single gas tank. Theoretically, the Arch can be dived on a single 11 Litre tank, and often has been, but this is dangerously close to the minimum gas requirement for the dive and depends on a fit and relaxed diver with a low gas consumption rate committing no errors or hesitations during the dive. Diving the Arch without a stage tank and without adequate gas planning has resulted in drowning or DCS.
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