Blue Hole

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

The Blue Hole is a submarine sinkhole (a kind of cave), around 130 m deep. There is a shallow opening around 6 m deep, known as 'the saddle', opening out to the sea, and a 26 m long tunnel, known as the arch, the top of which lies at a depth of 52 m. 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". The site is signposted by a sign that says "Blue hole: Easy entry". 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 52 m depth. This is beyond the PADI recreational diving limit (40 mz), and the effect of nitrogen narcosis will be significant at this depth. Divers who miss the tunnel sometimes continue descending hoping to find the tunnel farther down and become increasingly narced.

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 10 m long but measurements have shown it is 26 m 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 divesite is considered unsuitable for beginners and a potential trap for even experienced divers.
Beach and surface of the water at Blue Hole

Divers who want to go through the Arch should be suitably trained and equipped: this would usually include an anoxic mixed-gas qualification (e.g. a Trimix qualification from a technical diving training agency such as DSAT or TDI), technical diving equipment such as redundant gas supply, redundant large-capacity buoyancy control device and an anoxic gas mix such as trimix.

The Egyptian authorities claim that 40 divers have died at this site since records began; however, many local dive guides believe that the authorities are deliberately underestimating the numbers and that there have actually been at least twice that many fatalities.

Causes of death:

When diving on standard air at a depth of 90 meters, the narcosis will be so severe that a person can lose all survival instinct. There have been cases reported where people have been so narced as to remove the regulator from their mouth and offer it to a fish.

Another danger and possible cause of the regulator falling out of his mouth is Central Nervous System (CNS) Oxygen Toxicity, which causes convulsions and can be triggered by breathing a partial pressure of oxygen higher than 1.4 ATM, at 90 meters it would be 2.1 ATM, and be a very high risk indeed, this is why tech divers dive with less oxygen in the mix when diving this deep (for 90 meters, the max would be 14% oxygen in the gas mixture, and the mix would be at least three gases to reduce the partial pressure of each gas).

**Dive the Arch ONLY if you are a very advanced AND technical diver !!! NO single tank dives to the arch!**

Similar Dive Sites to Blue Hole

• 

  The Bells

• 

  Moray Garden

• 

  Coral Garden

• 

  Bannerfish Bay