Red Sea

Red Sea
Coordinates	22°N 38°E / 22°N 38°E / 22; 38Coordinates: 22°N 38°E / 22°N 38°E / 22; 38
Max. length	2,250 km (1,400 mi)
Max. width	355 km (221 mi)
Surface area	438,000 km2 (169,000 sq mi)
Average depth	490 m (1,610 ft)
Max. depth	2,211 m (7,254 ft)
Water volume	233,000 km3 (56,000 cu mi)

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 (leading to the Suez Canal). The Red Sea is a Global 200 ecoregion. The sea is underlain by the Red Sea Rift which is part of the Great Rift Valley.

The Red Sea has a surface area of roughly 438,000 km² (169,100 mi²).^[2][3] It is about 2250 km (1398 mi) long and, at its widest point, 355 km (220.6 mi) wide. It has a maximum depth of 2211 m (7254 ft) in the central median trench, and an average depth of 490 m (1,608 ft). However, there are also extensive shallow shelves, noted for their marine life and corals. The sea is the habitat of over 1,000 invertebrate species, and 200 soft and hard corals. It is the world's northernmost tropical sea.

Extent

The International Hydrographic Organization defines the limits of the Red Sea as follows:^[4]

On the North. The Southern limits of the Gulfs of Suez [A line running from Ràs Muhammed (27°43'N) to the South point of Shadwan Island (34°02'E) and thence Westward on a parallel (27°27'N) to the coast of Africa] and Aqaba [A line running from Ràs al Fasma Southwesterly to Requin Island (27°57′N 34°36′E / 27.950°N 34.600°E / 27.950; 34.600) through Tiran Island to the Southwest point thereof and thence Westward on a parallel (27°54'N) to the coast of the Sinaï Peninsula].

On the South. A line joining Husn Murad (12°40′N 43°30′E / 12.667°N 43.500°E / 12.667; 43.500) and Ras Siyyan (12°29′N 43°20′E / 12.483°N 43.333°E / 12.483; 43.333).

Name

Red Sea is a direct translation of the Greek Erythra Thalassa (Ερυθρὰ Θάλασσα) and Latin Mare Rubrum (alternatively Sinus Arabicus, literally "Arabian Gulf"), Arabic Al-Baḥr Al-Aḥmar (البحر الأحمر) or Baḥr Al-Qalzam(بحر القلزم), Somali Badda Cas and Tigrinya Qeyyiḥ bāḥrī (ቀይሕ ባሕሪ). The name of the sea may signify the seasonal blooms of the red-coloured Trichodesmium erythraeum near the water's surface.^[5] A theory favored by some modern scholars is that the name red is referring to the direction South, just as the Black Sea's name may refer to North. The basis of this theory is that some Asiatic languages used color words to refer to the cardinal directions.^[6] Herodotus on one occasion uses Red Sea and Southern Sea interchangeably.^[7]

Historically, it was also known to western geographers as Mare Mecca (Sea of Mecca), and Sinus Arabicus (Gulf of Arabia).^[8] Some ancient geographers called the Red Sea the Arabian Gulf^[9] or Gulf of Arabia.^[10][11]

The association of the Red Sea with the Biblical account of the Israelite Crossing the Red Sea is ancient, and was made explicit in the Septuagint translation of the Book of Exodus from Hebrew to Koine Greek in approximately the third century B.C. In that version, the Hebrew Yam Suph (ים סוף) is translated as Erythra Thalassa (Red Sea). (See also the more recent suggestion that the Yam Suph of the Exodus refers to a Sea of Reeds). The Red Sea is one of four seas named in English after common color terms — the others being the Black Sea, the White Sea and the Yellow Sea. The direct rendition of the Greek Erythra thalassa in Latin as Mare Erythraeum refers to the north-western part of the Indian Ocean, and also to a region on Mars.

History

The earliest known exploration of the Red Sea was conducted by ancient Egyptians, as they attempted to establish commercial routes to Punt. One such expedition took place around 2500 BC, and another around 1500 BC ( by Hatshepsut ). Both involved long voyages down the Red Sea.^[12] The Biblical Book of Exodus tells the story of the Israelites' crossing of a body of water, which the Hebrew text calls Yam Suph. Yam Suph was traditionally identified as the Red Sea. The account is part of the Israelites' escape from slavery in Egypt. Yam Suph can also been translated as Sea of Reeds.

In the 6th century BC, Darius the Great of Persia sent reconnaissance missions to the Red Sea, improving and extending navigation by locating many hazardous rocks and currents. A canal was built between the Nile and the northern end of the Red Sea at Suez. In the late 4th century BC, Alexander the Great sent Greek naval expeditions down the Red Sea to the Indian Ocean. Greek navigators continued to explore and compile data on the Red Sea. Agatharchides collected information about the sea in the 2nd century BC. The Periplus of the Erythraean Sea ("Periplus of the Red Sea"), a Greek periplus written by an unknown author around the 1st century AD, contain a detailed description of the Red Sea's ports and sea routes.^[13] The Periplus also describes how Hippalus first discovered the direct route from the Red Sea to India.

The Red Sea was favored for Roman trade with India starting with the reign of Augustus, when the Roman Empire gained control over the Mediterranean, Egypt, and the northern Red Sea. The route had been used by previous states but grew in the volume of traffic under the Romans. From Indian ports goods from China were introduced to the Roman world. Contact between Rome and China depended on the Red Sea, but the route was broken by the Aksumite Empire around the 3rd century AD.^[14]

During the Middle Ages, the Red Sea was an important part of the Spice trade route. In 1513, trying to secure that channel to Portugal, Afonso de Albuquerque laid siege to Aden.^[15] but was forced to retreat. They cruised the Red Sea inside the Bab al-Mandab, as the first European fleet to have sailed these waters.

In 1798, France ordered General Bonaparte to invade Egypt and take control of the Red Sea. Although he failed in his mission, the engineer Jean-Baptiste Lepère, who took part in it, revitalised the plan for a canal which had been envisaged during the reign of the Pharaohs. Several canals were built in ancient times from the Nile to the Red Sea along or near the line of the present Sweet Water Canal, but none lasted for long. The Suez Canal was opened in November 1869. At the time, the British, French, and Italians shared the trading posts. The posts were gradually dismantled following the First World War. After the Second World War, the Americans and Soviets exerted their influence whilst the volume of oil tanker traffic intensified. However, the Six Day War culminated in the closure of the Suez Canal from 1967 to 1975. Today, in spite of patrols by the major maritime fleets in the waters of the Red Sea, the Suez Canal has never recovered its supremacy over the Cape route, which is believed to be less vulnerable.

Oceanography

The Red Sea lies between arid land, desert and semi-desert. The main reasons for the better development of reef systems along the Red Sea is because of its greater depths and an efficient water circulation pattern, The Red Sea water mass exchanges its water with the Arabian Sea, Indian Ocean via the Gulf of Aden. These physical factors reduce the effect of high salinity caused by evaporation water in the north and relatively hot water in the south.

The climate of the Red Sea is the result of two distinct monsoon seasons; a northeasterly monsoon and a southwesterly monsoon. Monsoon winds occur because of the differential heating between the land surface and sea. Very high surface temperatures coupled with high salinities makes this one of the warmest and saltiest bodies of seawater in the world. The average surface water temperature of the Red Sea during the summer is about 26 °C (79 °F) in the north and 30 °C (86 °F) in the south, with only about 2 °C (3.6 °F) variation during the winter months. The overall average water temperature is 22 °C (72 °F). Today surface water temperatures remain relatively constant at 21–25 °C (70–77 °F). Temperature and visibility remain good to around 200 m (656 ft). The sea is known for its strong winds and unpredictable local currents.

The rainfall over the Red Sea and its coasts is extremely low, averaging 0.06 m (2.36 in) per year. The rain is mostly in the form of showers of short spells, often associated with thunderstorms and occasionally with dust storms. The scarcity of rainfall and no major source of fresh water to the Red Sea result in the excess evaporation as high as 205 cm (81 in) per year and high salinity with minimal seasonal variation. A recent underwater expedition to the Red Sea offshore from Sudan and Eritrea^[16] found surface water temperatures 28 °C in winter and up to 34 °C in the summer, but despite that extreme heat the coral was healthy with much fish life with very little sign of coral bleaching, with only 9% infected by thalassomonas loyana, the 'white plague' agent. Favia favus coral there harbours a virus, BA3, which kills T.loyana.^[17] Plans are afoot to use samples of these corals' apparently heat-adapted commensal algae to salvage bleached coral elsewhere.

Salinity

The Red Sea is one of the most saline bodies of water in the world, owing to high evaporation. Salinity ranges from between ~36 ‰ in the southern part because of the effect of the Gulf of Aden water and reaches 41 ‰ in the northern part, owing mainly to the Gulf of Suez water and the high evaporation. The average salinity is 40 ‰. (Average salinity for the world's seawater is ~35 ‰ on the Practical Salinity Scale, or PPS; that translates to 3.5% actual dissolved salts.)

The salinity of the Red Sea is greater than the world average, approximately 4 percent. This is due to several factors:

1. High rate of evaporation and very little precipitation.
2. Lack of significant rivers or streams draining into the sea.
3. Limited connection with the Indian Ocean, which has lower water salinity.

Tidal range

In general tide ranges between 0.6 m (2.0 ft) in the north, near the mouth of the Gulf of Suez and 0.9 m (3.0 ft) in the south near the Gulf of Aden but it fluctuates between 0.20 m (0.66 ft) and 0.30 m (0.98 ft) away from the nodal point. The central Red Sea (Jeddah area) is therefore almost tideless, and as such the annual water level changes are more significant. Because of the small tidal range the water during high tide inundates the coastal sabkhas as a thin sheet of water up to a few hundred metres rather than inundating the sabkhas through a network of channels. However, south of Jeddah in the Shoiaba area the water from the lagoon may cover the adjoining sabkhas as far as 3 km (2 mi) whereas, north of Jeddah in the Al-kharrar area the sabkhas are covered by a thin sheet of water as far as 2 km (1.2 mi). The prevailing north and northeastern winds influence the movement of water in the coastal inlets to the adjacent sabkhas, especially during storms. Winter mean sea level is 0.5 m (1.6 ft) higher than in summer. Tidal velocities passing through constrictions caused by reefs, sand bars and low islands commonly exceed 1–2 m/s (3–6.5 ft/s). Coral reefs in the Red Sea are near Egypt, Eritrea, Israel, Saudi Arabia, and Sudan.

Current

In the Red Sea detailed current data is lacking, partially because they are weak and variable both spatially and temporally. Temporal and spatial currents variation is as low as 0.5 m (1.6 ft) and are governed all by wind. During the summer, NW winds drive surface water south for about four months at a velocity of 15–20 cm/s (6–8 in/s), whereas in winter the flow is reversed resulting in the inflow of water from the Gulf of Aden into the Red Sea. The net value of the latter predominates, resulting in an overall drift to the northern end of the Red Sea. Generally, the velocity of the tidal current is between 50–60 cm/s (20–23.6 in/s) with a maximum of 1 m/s (3.3 ft/s) at the mouth of the al-Kharrar Lagoon. However, the range of the north-northeast current along the Saudi coast is 8–29 cm/s (3–11.4 in/s).

Wind regime

With the exception of the northern part of the Red Sea, which is dominated by persistent north-west winds, with speeds ranging between 7 km/h (4.3 mph) and 12 km/h (7.5 mph), the rest of the Red Sea and the Gulf of Aden are subjected to the influence of regular and seasonally reversible winds. The wind regime is characterized by both seasonal and regional variations in speed and direction with average speed generally increasing northward.

Wind is the driving force in the Red Sea for transporting the material either as suspension or as bedload. Wind induced currents play an important role in the Red Sea in initiating the process of resuspension of bottom sediments and transfer of materials from sites of dumping to sites of burial in quiescent environment of deposition. Wind generated current measurement is therefore important in order to determine the sediment dispersal pattern and its role in the erosion and accretion of the coastal rock exposure and the submerged coral beds.

Geology

The Red Sea was formed by Arabia being split from Africa by movement of the Red Sea Rift. This split started in the Eocene and accelerated during the Oligocene. The sea is still widening, and it is considered that it will become an ocean in time (as proposed in the model of John Tuzo Wilson). In 1949, a deep water survey reported anomalously hot brines in the central portion of the Red Sea. Later work in the 1960s confirmed the presence of hot, 60 °C (140 °F), saline brines and associated metalliferous muds. The hot solutions were emanating from an active subseafloor rift. The high salinity of the waters was not hospitable to living organisms.^[18]

Sometimes during the Tertiary period the Bab el Mandeb closed and the Red Sea evaporated to an empty, hot, dry salt-floored sink. Effects causing this would have been:

• A "race" between the Red Sea widening and Perim Island erupting filling the Bab el Mandeb with lava.
• The lowering of world sea level during the Ice Ages because of much water being locked up in the ice caps.

A number of volcanic islands rise from the center of the sea. Most are dormant, but in 2007 Jabal al-Tair island, in the Bab el Mandeb strait, erupted violently. An eruption among the nearby Zubair islands followed in 2011.^[19]

Mineral resources

In terms of mineral resources the major constituents of the Red Sea sediments are as follows:

• Biogenic constituents:

Nanofossils, foraminifera, pteropods, siliceous fossils

• Volcanogenic constituents:

Tuffites, volcanic ash, montmorillonite, cristobalite, zeolites

• Terrigenous constituents:

Quartz, feldspars, rock fragments, mica, heavy minerals, clay minerals

• Authigenic minerals:

Sulfide minerals, aragonite, Mg-calcite, protodolomite, dolomite, quartz, chalcedony.

• Evaporite minerals:

Magnesite, gypsum, anhydrite, halite, polyhalite

• Brine precipitate:

Fe-montmorillonite, goethite, hematite, siderite, rhodochrosite, pyrite, sphalerite, anhydrite.

Living resources

The Red Sea is a rich and diverse ecosystem. More than 1200 species of fish^[20] have been recorded in the Red Sea, and around 10% of these are found nowhere else.^[21] This also includes 42 species of deepwater fish.^[20]

The rich diversity is in part due to the 2,000 km (1,240 mi) of coral reef extending along its coastline; these fringing reefs are 5000–7000 years old and are largely formed of stony acropora and porites corals. The reefs form platforms and sometimes lagoons along the coast and occasional other features such as cylinders (such as the Blue Hole (Red Sea) at Dahab). These coastal reefs are also visited by pelagic species of red sea fish, including some of the 44 species of shark.

The Red Sea also contains many offshore reefs including several true atolls. Many of the unusual offshore reef formations defy classic (i.e., Darwinian) coral reef classification schemes, and are generally attributed to the high levels of tectonic activity that characterize the area.

The special biodiversity of the area is recognized by the Egyptian government, who set up the Ras Mohammed National Park in 1983. The rules and regulations governing this area protect local marine life, which has become a major draw for diving enthusiasts.

Divers and snorkellers should be aware that although most Red Sea species are innocuous, a few are hazardous to humans: see Red Sea species hazardous to humans.^[22]

Other marine habitats include sea grass beds, salt pans, mangroves and salt marshes.

Desalination plants

There is extensive demand of desalinated water to meet the requirement of the population and the industries along the Red Sea.

There are at least 18 desalination plants along the Red Sea coast of Saudi Arabia which discharge warm brine and treatment chemicals (chlorine and anti-scalants) that may cause bleaching and mortality of corals and diseases to the fish stocks. Although this is only a localized phenomenon, it may intensify with time and have a profound impact on the fishing industry.^[23]

The water from the Red Sea is also utilized by oil refineries and cement factories for cooling purposes. Used water drained back into the coastal zones may cause harm to the nearshore environment of the Red Sea.

Security

The Red Sea is part of the sea roads between Europe, the Persian Gulf and East Asia, and as such has heavy shipping traffic. Piracy in Somalia occurs principally near the area of the Gulf of Aden south of the sea. Government-related bodies with responsibility to police the Red Sea area include the Port Said Port Authority, Suez Canal Authority and Red Sea Ports Authority of Egypt, Jordan Maritime Authority, Israel Port Authority, Saudi Ports Authority and Sea Ports Corporation of Sudan.

Facts and figures

• Length: ~2,250 km (1,398.1 mi) - 79% of the eastern Red Sea with numerous coastal inlets
• Maximum Width: ~ 306–355 km (190–220 mi)– Massawa (Eritrea)
• Minimum Width: ~ 26–29 km (16–18 mi)- Bab el Mandeb Strait (Yemen)
• Average Width: ~ 280 km (174.0 mi)
• Average Depth: ~ 490 m (1,607.6 ft)
• Maximum Depth: ~2,211 m (7,253.9 ft)
• Surface Area: 438-450 x 10² km² (16,900–17,400 sq mi)
• Volume: 215–251 x 10³ km³ (51,600–60,200 cu mi)

• Approximately 40% of the Red Sea is quite shallow (under 100 m/330 ft), and about 25% is under 50 m (164 ft) deep.
• About 15% of the Red Sea is over 1,000 m (3,300 ft) depth that forms the deep axial trough.
• Shelf breaks are marked by coral reefs
• Continental slope has an irregular profile (series of steps down to ~500 m or 1,640 ft)
• Centre of Red Sea has a narrow trough (~ 1,000 m or 3,281 ft; some deeps may exceed 2,500 m or 8,202 ft)

Tourism

The sea is known for its spectacular recreational diving sites, such as Ras Mohammed, SS Thistlegorm (shipwreck), Elphinstone Reef, The Brothers, Daedalus Reef, St.John's Reef, Rocky Island in Egypt^[24] and less known sites in Sudan such as Sanganeb, Abington, Angarosh and Shaab Rumi.

The Red Sea became a sought-after diving destination after the expeditions of Hans Hass in the 1950s, and later by Jacques-Yves Cousteau. Popular tourist resorts include El Gouna, Hurghada, Safaga, Marsa Alam, on the western shore of the Red Sea, and Sharm-El-Sheikh, Dahab, and Taba on the Egyptian side of Sinaï, as well as Aqaba in Jordan and Eilat in Israel in an area known as the Red Sea Riviera.

The popular tourist beach of Sharm el-Sheikh was closed to all swimming in December 2010 due to several serious shark attacks, including one fatality. As of December 2010, scientists are investigating the attacks and have identified, but not verified, several possible causes including over-fishing which causes large sharks to hunt closer to shore, tourist boat operators who chum offshore for shark-photo opportunities, and reports of ships throwing dead livestock overboard. The sea's narrow width, significant depth, and sharp drop-offs, all combine to form a geography where large deep-water sharks can roam in hundreds of meters of water, yet be within a hundred meters of swimming areas.

Bordering countries

The Red Sea may be geographically divided into three sections: the Red Sea proper, and in the north, the Gulf of Aqaba and the Gulf of Suez. The six countries bordering the Red Sea proper are:

• Eastern shore:
  •  Saudi Arabia
  •  Yemen
• Western shore:
  •  Egypt
  •  Sudan
  •  Eritrea
  •  Djibouti

The Gulf of Suez is entirely bordered by Egypt. The Gulf of Aqaba borders Egypt, Israel, Jordan and Saudi Arabia.

In addition to the standard geographical definition of the six countries bordering the Red Sea cited above, areas such as Somalia and Ethiopia are sometimes also described as Red Sea territories. This is primarily due to their proximity to and geological similarities with the nations facing the Red Sea and/or political ties with said areas.^[25][26]

Towns and cities

Towns and cities on the Red Sea coast (including the coasts of the Gulfs of Aqaba and Suez) include:

Al Hudaydah (الحديدة) Al Lith (الليِّث) Al Qunfudhah (القنفذة) Al-Qusair (القصير) Al Wajh (الوجه) Aqaba (العقبة) Asseb (ዓሳብ) Dahab (دهب) Duba (ضباء) Eilat (אילת)

El Gouna (الجونة) El Suweis (السويس) / Hala'ib (حلايب) (disputed) Haql (حقل) Hirgigo (ሕርጊጎ) Hurghada (الغردقة) Jeddah (جدة) Jazan (جازان) Marsa Alam (مرسى علم) Massawa (ምጽዋ)

Nuweiba (نويبع) Port Safaga (ميناء سفاجا) Port Sudan (بورت سودان) Rabigh (رابغ) Sharm el Sheikh (شرم الشيخ) Soma Bay (سوما باي) Suakin (سواكن) Taba (طابا) Thuwal (ثول) Yanbu (ينبع)

See also

• Benjamin Kahn
• MS al-Salam Boccaccio 98 ferry disaster
• Red Sea dam
• Robert Moresby

References

Further reading

• Hamblin, W. Kenneth & Christiansen, Eric H. (1998). Earth's Dynamic Systems (8th ed.). Upper Saddle River: Prentice-Hall. ISBN 0-13-745373-6 

External links

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• Red Sea Coral Reefs
• Red Sea Photography
• Potts, D., R. Talbert, T. Elliott, S. Gillies. "Places: 39290 (Arabicus Sinus/Erythr(ae)um/Rubrum Mare)". Pleiades. Retrieved March 8, 2012. 

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v t e Countries bordering the Red Sea  Djibouti  Egypt  Eritrea  Ethiopia  Israel  Jordan  Saudi Arabia  Somalia  Sudan  Yemen