The strait of Tiran lies at the mouth of the Gulf of Aqaba and is shown to the west by the coast of Sinai and to the east by the island of Tiran. In the middle of this canal are 4 coral reefs lying in a northeast-southwest direction that get there named after the 19th -century English cartographers who drew the first nautical map of this region – Jackson Reef, Woodhouse Reef, Thomas Reef and Gordon Reef. These reefs divide this strait into two canals: to the east is the so-called Grafton Passage, which is used exclusively by ships going northwards, while to the west is the Enterprise Passage for ships heading south. East of the island of Tiran and the nearby island of Sanafir – both part of Saudi Arabia but granted to Egypt for military defence–the configuration of the canal floor makes navigation impossible.
On a level with the strait of Tiran, the Gulf of Aqaba passes from an average width of 10-12 to 2.4 miles, while the floor goes from a depth of 1,270 meters to only 71 meters in Grafton Passage and 250 meters in Enterprise Passage.
This particular configuration of the strait reduces deep water exchange between the Gulf of Aqaba and the rest of the Red Sea on the one hand, causing an increase of saltiness and temperature, while on the other hand it gives rise to an increase in the speed of the tidal currents and the average height of the waves moved by the wind which, chanelled by the largemontains of Sinai and Saudi Arabia, is in turn subject to acceleration. The peculiar topographical arrangement of these reefs and the presence of insisting air moving from the north, which are stronger in the morning and calmer in the afternoon, means their western and northern sides (or outside) are much more exposed to the action of the waves than the eastern and southern ones, which are inside and sheltered.
The strong currents characterizing the Strait of Tiran transport great quantities of plankton and other nutrient material every day, thus supplying a great deal of food to the corals and hence to the reef fish, which in turn are eaten by the large pelagic predators such as barracuda, jackfish, tuna and above all sharks, which are always present in this zone. Consequently, scuba divers in the waters of Tiran are sure to see not only an infinite number of corals but also rich fauna, both reef and pelagic.
