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Beach and surface of the water at Blue Hole

Blue Hole is a diving location on east Sinai, a few kilometres north of Dahab on the coast of the Red Sea.

The Blue Hole is a submarine Pothole (a kind of cave) it is ~100 meter deep with a ~50 meter wide opening just offshore and just underwater. The hole itself and the surrounding area has an abundance of coral and reef fish.

The Blue Hole is notorious for the number of diving fatalities which have occurred there earning it the sobriquet, "World's Most Dangerous Dive Site" and the nickname "Diver's Cemetery". Accidents are frequently caused when divers attempt to find the tunnel through the reef (known as "The Arch") connecting the Blue Hole and open water at about 60m depth, 60m is beyond the PADI recreational diving limit (40m) and nitrogen narcosis begins to have an influence. Divers who miss the tunnel sometimes continue descending hoping to find the tunnel lower down and become increasingly narcotised. 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 and the fact that most light enters from outside it appears shorter than it really is, divers report that the Arch appears less than 10m long but measurements have shown it is 26m 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.

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 site is considered unsuitable for beginners and a potential trap even for experienced divers.

Divers wishing to traverse the Arch should do so only after appropriate training and experience possibly including: use of multiple cylinders (a twin set may be insufficient for the dive), mixed gases (reduced nitrogen mixtures should be used at this depth), decompression (even if the dive plan does not require decompression delays could easily make it necessary) and overhead environments. A perfect control of one's buoyancy and diving weighting system is also required.

Two freedivers at Blue Hole.

The Egyptian authorities claim that 40 divers have died at this site since records begin; however, local dive guides frequently believe that the authorities are deliberately understating the numbers and that there have actually been twice that many fatalities - and possibly even more.

The adjacent shore is lined with restaurants and Snorkel hire shops. SCUBA tours are available from nearby Dahab. It is also a toilet stop on several camel treks. The access road is 4 wheel drive only (the taxis in Dahab are mainly jeeps and should have no difficulty).

Saudi Arabia is clearly visible across the Red Sea.

Coordinates: 28°34′20″N, 34°32′13.5″E