Blue Hole is a diving location on east Sinai

Sinai Peninsula

The Sinai Peninsula or Sinai is a triangular peninsula in Egypt about in area. It is situated between the Mediterranean Sea to the north, and the Red Sea to the south, and is the only part of Egyptian territory located in Asia as opposed to Africa, effectively serving as a land bridge between two...

, a few kilometres north of Dahab

Dahab

Dahab is a small town situated on the southeast coast of the Sinai Peninsula in Egypt. Formerly a Bedouin fishing village, located approximately northeast of Sharm el-Sheikh, Dahab is considered to be one of the Sinai's most treasured diving destinations...

, Egypt

Egypt

Egypt , officially the Arab Republic of Egypt, Arabic: , is a country mainly in North Africa, with the Sinai Peninsula forming a land bridge in Southwest Asia. Egypt is thus a transcontinental country, and a major power in Africa, the Mediterranean Basin, the Middle East and the Muslim world...

 on the coast of the Red Sea

Red Sea

The Red Sea is a seawater inlet of the Indian Ocean, lying between Africa and Asia. The connection to the ocean is in the south through the Bab el Mandeb strait and the Gulf of Aden. In the north, there is the Sinai Peninsula, the Gulf of Aqaba, and the Gulf of Suez...

.

The Blue Hole is a submarine sinkhole

Sinkhole

A sinkhole, also known as a sink, shake hole, swallow hole, swallet, doline or cenote, is a natural depression or hole in the Earth's surface caused by karst processes — the chemical dissolution of carbonate rocks or suffosion processes for example in sandstone...

 (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 56 m. The hole itself and the surrounding area has an abundance of coral

Coral

Corals are marine animals in class Anthozoa of phylum Cnidaria typically living in compact colonies of many identical individual "polyps". The group includes the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton.A coral "head" is a colony of...

 and reef

Reef

In nautical terminology, a reef is a rock, sandbar, or other feature lying beneath the surface of the water ....

 fish.

Dangers

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 maximum recreational diving limit of 40m and the effect of nitrogen narcosis

Nitrogen narcosis

Narcosis while diving , is a reversible alteration in consciousness that occurs while scuba diving at depth. The Greek word ναρκωσις is derived from narke, "temporary decline or loss of senses and movement, numbness", a term used by Homer and Hippocrates...

 is 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.

Diving through the arch requires suitable training and equipment, usually including a mixed-gas qualification from a technical diving training agency, technical diving

Technical diving

Technical diving is a form of scuba diving that exceeds the scope of recreational diving...

 equipment such as redundant gas supply, redundant large-capacity buoyancy control device and a breathing gas with reduced nitrogen content 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.

A famous (and videotaped) death in the Blue hole is that of Yuri Lipski, an Israeli-Russian diver who died at 91.6 meters below the surface. Lipski was, tragically, an unfortunate victim of inexperience and lack of proper equipment.

External links

• A short description of all dive sites in Dahab