The Red Sea has a surface area of roughly 438,000 km2 (169,000 sq mi),[1] is about 2,250 km (1,400 mi) long, and 355 km (221 mi) wide at its widest point. It has an average depth of 490 m (1,610 ft), and in the central Suakin Trough, it reaches its maximum depth of 3,040 m (9,970 ft).[2]
The Red Sea is quite shallow, with approximately 40% at less than 100 m (330 ft) deep, and approximately 25% at less than 50 m (160 ft) deep. The extensive shallow shelves are noted for their marine life andcorals. More than 1,000invertebrate species and 200 types of soft and hard coral live in the sea. The Red Sea is the world's northernmosttropical sea and has been designated aGlobal 200 ecoregion.
The English termRed Sea is a direct translation of theAncient GreekErythrà Thálassa (Ἐρυθρὰ Θάλασσα). The sea itself was once referred to as theErythraean Sea by Europeans. As well asMare Rubrum inLatin (alternativelySinus Arabicus, literally "Arabian Gulf"), the Romans called itPontus Herculis (Sea of Hercules).[5] Other designations include the Arabicالبحر الأحمر,Al-Baḥr Al-Aḥmar (alternativelyبحر القلزم,Baḥr Al-Qulzum, 'the Sea ofClysma'); the Copticⲫⲓⲟⲙ ̀ⲛϣⲁⲣⲓ,Phiom ̀nšari; theSyriacܝܡܐ ܣܘܡܩܐ,Yammāʾ summāqā; the SomaliBadda Cas; and the Tigrinyaቀይሕ ባሕሪ,Qeyyiḥ bāḥrī. The name of the sea may signify the seasonal blooms of the red-colouredTrichodesmium erythraeum near the water's surface.[6] A theory favored by some modern scholars is that the namered refers to the direction south, just as theBlack Sea's name may refer to the north. The basis of this theory is that someAsiatic languages used color words to refer to thecardinal directions.[7]Herodotus on one occasion uses the Red Sea and Southern Sea interchangeably.[8]
The nameYam Suph (Hebrew:ים סוף,lit. 'Sea of Reeds') is of biblical origin.
The name in Copticⲫⲓⲟⲙ 'ⲛϩⲁϩPhiom Enhah ("Sea of Hah") is connected tothe Ancient Egyptian rootḥ-ḥ which refers to water and sea (for example the names of theOgdoad godsHeh and Hauhet).[9]
Historically, it was also known to western geographers asMare Mecca (Sea ofMecca), andSinus Arabicus (Gulf ofArabia).[10] Some ancient geographers called the Red Sea the Arabian Gulf[11] or the Gulf of Arabia.[12]
The association of the Red Sea with thebiblical account of the Israelitescrossing the Red Sea is ancient. It was made explicit in theSeptuagint translation of theBook of Exodus fromHebrew toKoine Greek in approximately the third century BC. In that version, theYam Suph (Hebrew:ים סוף,lit. 'Sea of Reeds') is translated asErythra Thalassa (Red Sea).
The Red Sea is one of four seas named in English after commoncolours – the others being theBlack Sea, theWhite Sea and theYellow Sea. The direct rendition of the GreekErythra thalassa in Latin asMare Erythraeum refers to the north-western part of theIndian Ocean, and also to a region onMars.
The earliest known exploration of the Red Sea was conducted byancient Egyptians, as they attempted to establish commercial routes toPunt. One such expedition took place around 2500 BC, and another around 1500 BC (byHatshepsut). Both involved long voyages down the Red Sea.[13]
In the 6th century BC,Darius the Great, who was a prominent ruler of theAchaemenid Empire in Persia, undertook significant efforts to improve and extend navigation in the Red Sea. He sent reconnaissance missions to explore the Red Sea area and to identify its various navigational hazards, such as rocks and currents. This effort was significant, as it contributed to safer and more efficient navigation routes.[15]
In addition to the maritime explorations, during the reign of Darius the Great, a canal was constructed linking the Nile River to the northern end of the Red Sea at Suez. This canal is sometimes referred to as the ancient Suez Canal. It played a pivotal role in improving trade and communication between the Nile Valley and the Red Sea, and beyond to the Indian Ocean. This canal was a predecessor to the modernSuez Canal, which was constructed in the 19th century and continues to be one of the world's most important waterways.[16]
The construction of the canal during Darius's reign is evidenced by ancient records, including inscriptions. Darius commemorated the completion of the canal by creating stelae (stone monuments) with inscriptions in several languages, describing the construction and its benefits. The canal not only facilitated trade but also solidified Darius's control over Egypt and enhanced the Achaemenid Empire's economic and political power in the region.
In the late 4th century BC,Alexander the Great sent Greek naval expeditions down the Red Sea to theIndian Ocean. Greek navigators continued to explore and compile data on the Red Sea.Agatharchides collected information about the sea in the 2nd century BC. ThePeriplus of the Erythraean Sea ("Periplus of the Red Sea"), aGreekperiplus written by an unknown author around the 1st century, contains a detailed description of the Red Sea's ports and sea routes.[17] The Periplus also describes howHippalus first discovered the direct route from the Red Sea toIndia.
The Red Sea was favored forRoman trade with India starting with the reign ofAugustus, when theRoman 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 fromChina were introduced to theRoman world. Contact between Rome and China depended on the Red Sea, but the route was broken by theAksumite Empire around the 3rd century AD.[18]From antiquityuntil the 20th century, the Red Sea was also a trade route for theRed Sea slave trade from Africa to the Middle East.[19]
During theMiddle Ages, the Red Sea was an important part of thespice trade route. In 1183,Raynald of Châtillon launched a raid down the Red Sea to attack the Muslim pilgrim convoys to Mecca.[20]: 143–144 The possibility that Raynald's fleet might sack the holy cities of Mecca and Medina caused fury throughout the Muslim world.[20]: 146–147 However, it appears that Raynald's target was the lightly armed Muslim pilgrim convoys, rather than the well-guarded cities of Mecca and Medina, and the belief in the Muslim world that Raynald was seeking to sack the holy cities, due to the proximity of those cities to the areas that Raynald raided.[20]: 152–153
In 1513, trying to secure that channel to Portugal,Afonso de Albuquerque laidsiege to Aden[21] but was forced to retreat. They cruised the Red Sea inside theBab al-Mandab, as the first fleet from Europe in modern times to have sailed these waters. Later in 1524, the city was delivered to Governor Heitor da Silveira as an agreement for protection from theOttomans.[22]In 1798,France ordered GeneralNapoleon to invadeEgypt and take control of the Red Sea. Although he failed in his mission, the engineerJean-Baptiste Lepère, who took part in it, revitalised the plan for a canal which had been envisaged during the reign of thePharaohs. Several canals were built in ancient times from the Nile to the Red Sea along or near the line of the presentSweet Water Canal, but none lasted for long. TheSuez Canal was opened in November 1869. During the first half of the 20th century, theRed Sea slave trade attracted substantial international condemnation.
After theSecond World War, the Americans and Soviets exerted their influence whilst the volume of oil tanker traffic intensified. However, theSix-Day War culminated in the closure of the Suez Canal from 1967 to 1975. Today, despite the 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 to piracy.[23]
Iranian-backed YeminiHouthis have attacked Western ships, including warships, next to theBab al-Mandeb during theGaza war. One ship was hijacked and taken back to Yemen.[24]
Annotated view of the Nile and Red Sea, with a dust storm, viewed from theInternational Space Station[25]This video over the south-easternMediterranean Sea and down the coastline of the Red Sea was taken by the crew of Expedition 29 on board the International Space Station.
The Red Sea is between arid land,desert andsemi-desert.[26] Many regions of the coastal zone of the Red Sea possess large areas of vigorously growing coral and extensive reef complexes. Due to the tidal currents, low human population and the minimal development in this climatically inhospitable region, the Red Sea coral reefs are some of the healthiest reef environments in the world.[27] The Red Sea water mass-exchanges its water with theArabian Sea andIndian Ocean via theGulf of Aden. These physical factors reduce the effect of high salinity caused by evaporation in the north and relatively hot water in the south.[28]
Theclimate of the Red Sea is the result of twomonsoon seasons: a northeasterly monsoon and a southwesterly monsoon. Monsoon winds occur because of differential heating between the land and the sea. Very high surface temperatures and high salinity make 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). Temperature and visibility remain good to around 200 m (660 ft). The sea is known for its strong winds and unpredictable local currents.[citation needed]
Therainfall over the Red Sea and its coasts is extremely low, averaging 60 mm (2.36 in) per year. The rain is mostly short showers, often with thunderstorms and occasionally with duststorms. The scarcity of rainfall and no major source of fresh water to the Red Sea result in excess evaporation as high as 2,050 mm (81 in) per year and high salinity with minimal seasonal variation. A recent[when?] underwater expedition to the Red Sea offshore fromSudan andEritrea[29][verification needed] found surface water temperatures 28 °C (82 °F) in winter and up to 34 °C (93 °F) in the summer, but despite that extreme heat, the coral was healthy with much fish life with very little sign ofcoral bleaching, with only 9% infected byThalassomonas loyana, the 'white plague' agent.Favia favus coral there harbours a virus, BA3, which killsT. loyana.[30]Scientists are investigating the unique properties of these coral and theircommensalalgae to see if they can be used to salvage bleached coral elsewhere.[31]
The Red Sea is one of the saltiest bodies of water in the world, owing to high evaporation and low precipitation; no significant rivers or streams drain into the sea, and its southern connection to theGulf of Aden, an arm of the Indian Ocean, is narrow.[32] Itssalinity ranges from between ~36 ‰ in the southern part and 41 ‰ in the northern part around theGulf of Suez, with an average of 40 ‰. (Average salinity for the world'sseawater is ~35 ‰ on the Practical Salinity Scale, or PSU; that translates to 3.5% of actual dissolved salts).[33]
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 coastalsabkhas as a thin sheet of water up to a few hundred metres rather than flooding thesabkhas through a network of channels. However, south of Jeddah in theShoiaba area, the water from the lagoon may cover the adjoining sabkhas as far as 3 km (2 mi), whereas north ofJeddah in theAl-Kharrar area the sabkhas are covered by a thin sheet of water as far as 2 km (1.2 mi). The prevailing north and northeast 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 (3–7 ft/s). Coral reefs in the Red Sea are near Egypt, Eritrea, Israel, Saudi Arabia, and Sudan.[34]
Detailed information regarding current data is lacking, partially because the currents are weak and both spatially and temporally variable. The variation of temporal and spatial currents is as low as 0.5 m (1.6 ft)[clarification needed] and is governed all by the wind. During the summer, northwesterly 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 north end of the Red Sea. Generally, the velocity of the tidal current is 50–60 cm/s (20–24 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 in/s).[citation needed]
The northern part of the Red Sea is dominated by persistent north-westwinds, with speeds ranging between 7 km/h (4.3 mph) and 12 km/h (7.5 mph). The rest of the Red Sea and theGulf of Aden are subjected to regular and seasonally reversible winds. The windregime is characterized by seasonal and regional variations inspeed anddirection with average speed generally increasing northward.[35]
The wind is the driving force in the Red Sea to transport material as suspension or as bedload. Wind-induced currents play an important role in the Red Sea in resuspending bottom sediments and transferring materials from sites of dumping to sites of burial in a quiescent environment of deposition. Wind-generated currentmeasurement is therefore important to determine the sediment dispersal pattern and its role in the erosion and accretion of the coastal rock exposure and the submerged coral beds.[36]
The Red Sea was formed by theArabian Peninsula being split from theHorn of Africa by the movement of theRed Sea Rift. This split started in theEocene and accelerated during theOligocene. The sea is still widening (in 2005, following a three weeks oftectonic activity it had grown by 8 m [26 ft]),[37] and it is considered that it will become an ocean in time (as proposed in the model ofJohn Tuzo Wilson). In 1949, a deep water survey reported anomalously hotbrines 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 subseafloorrift.Lake Asal in Djibouti is eligible as an experimental site to study the evolution of the deep hot brines of the Red Sea.[38] By observing the strontium isotope composition of the Red Sea brines, it is possible to deduce how these salt waters found at the bottom of the Red Sea could have evolved in a similar way to Lake Asal, which ideally represents their compositional extreme.[38] The high salinity of the waters was not hospitable to living organisms.[39]
Sometime during theTertiary, theBab el Mandeb closed and the Red Sea evaporated to an empty hot dry salt-floored sink.[40] Effects causing this would have been:
A "race" between the Red Sea widening andPerim Islanderupting filling the Bab el Mandeb withlava.
The lowering of worldsea level during theIce Ages because of much water being locked up in theice caps.
Several volcanic islands rise from the center of the sea. Most are dormant. However, in 2007,Jabal al-Tair island in the Bab el Mandeb strait erupted violently. Two new islands were formed in 2011 and 2013 in theZubair Archipelago, a small chain of islands owned by Yemen. The first island, Sholan Island, emerged in an eruption in December 2011, and the second island, Jadid, emerged in September 2013.[41][42][43] Approximately 40% of the Red Sea is quite shallow at less than 100 m (330 ft) deep, with about 25% less than 50 m (160 ft) deep.[6]
Undiscovered oil reserves in the region have been estimated at 801.5 million cubic metres (5,041 million barrels). Undiscovered gas reserves in the region have been estimated at 3,180 billion cubic metres (112,349 billion cubic feet). Undiscovered natural gas reserves have been estimated at 489 million cubic metres (3,077 million barrels).[44] Most of these plays are controlled by the structure of the basin.[45] Normal faults are common as the Red Sea occupies an active diverging margin.[46] These targets are commonly found below the Salt deposits of theMiddle Miocene.
Modern development is focused on the following fields. The Durwara 2 Field was discovered in 1963, while the Suakin 1 Field and the Bashayer 1A Field were discovered in 1976, on the Egyptian side of the Red Sea. The Barqan Field was discovered in 1969, and the Midyan Field in 1992, both within the Midyan Basin on the Saudi Arabian side of the Red Sea. The 20-m thick Middle Miocene MaqnaFormation is an oil source rock in the basin.Oil seeps occur near theFarasan Islands, theDahlak Archipelago, along the coast of Eritrea, and in the southeastern Red Sea along the coasts of Saudi Arabia and Yemen.[47]
The Red Sea is a rich and diverse ecosystem. For example, more than 1200 fish species have been recorded in the Red Sea,[50] of which 10% are endemic, found nowhere else.[51]
Since the opening of the Suez Canal in November 1869, over a thousand marine species from the Red Sea—from plankton, seaweeds, invertebrates to fishes—have migrated northward and settled in theMediterranean Sea. To the point that a number of them now form a significant component of the Mediterranean ecosystem. The resulting change in biodiversity, without precedent in human memory, is currently accelerating, in particular for fishes according to surveys engaged by theMediterranean Science Commission.[52]
Red Sea coral and marine fish
The rich diversity of the Red Sea is in part due to the 2,000 km (1,240 mi) ofcoral reef extending along its coastline; these fringing reefs are 5000–7000 years old and are largely formed of stonyacropora andporite corals. The reefs form platforms and sometimes lagoons along the coast and occasionally other features such as cylinders (such as theBlue Hole (Red Sea) atDahab).
The Red Sea also hosts 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. Both offshore and coastal reefs are visited by pelagic species of fish, including many of the 44 recorded species of shark, and by many species (over 175) ofnudibranch, many of which are endemic to the Red Sea.[53] Other coastal Red Sea habitats includeseagrass beds,salt pans,mangroves andsalt marshes. Furthermore, the deep Red Seabrine pools have been extensively studied about their microbial life, characterized by their diversity and adaptation to extreme environments.
The high marine biodiversity of the area is recognized by the Egyptian government, which set up theRas Mohammed National Park in 1983. The rules and regulations governing this area protect local marine life. Ras Mohammed is one of the world's top 10 sites recognized by theInternational Union for Conservation of Nature for effective management of marine ecosystems, and the first marine protected area in Africa and in the Middle East region.[54]
Due to the high volume of maritime traffic, carrying 12–15% of global trade, the Red Sea is considered highly vulnerable to marine pollution, particularly oil spills. Academic literature has increasingly focused on both past disasters and predictive modelling. Studies have modelled spill trajectories and their environmental consequences.[55][56] Others have analysed the ecological impact of spills on coral reefs and marine biodiversity and assessed how chemical dispersants and specific oil compounds affect marine fauna and coastal ecosystems.[57][58][59] Public health literature has raised concerns over the spill's impact on respiratory illness and waterborne contamination in coastal populations.[60]
List of fauna species found in the Red Sea and the Gulf of Aqaba
There is extensive demand fordesalinated water to meet the needs 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 warmbrine and treatment chemicals (chlorine andanti-scalants) thatbleach and killcorals and cause diseases in the fish. This is only localized, but it may intensify with time and profoundly impact the fishing industry.[61]
The popular tourist beach of Sharm el-Sheikh was closed to all swimming in December 2010 due to several seriousshark attacks, including a fatality. As of December 2010, scientists are investigating the attacks and have identified, but not verified, several possible causes including overfishing 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 narrowness, 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. The Red Sea Project is building the highest quality accommodation and a wide range of facilities on the coastline in Saudi Arabia. This will allow people to visit the coastline of the Red Sea by the end of 2022 but will be fully finished by 2030.[66]
Houthi rebels in Yemen have increased attacks on shipping vessels since mid-November 2023. The blocking of Israeli-linked ships was in response to Israel's war onGaza.[63] In January 2024, it was reported that Red Sea shipping volumes had dropped to 30% of normal levels due to Houthi intervention.[69] In response, the US has announced a maritime coalition to defend shipping in the Red Sea for theOperation Prosperity Guardian.[63] In addition to the U.S.-led efforts, the European Union launched Operation Aspides in February 2024 to provide naval escorts and protect commercial shipping in the Red Sea.[70] In January 2025, the United Nations Security Council adopted Resolution 2768, calling for an end to Houthi attacks and demanding the release of detained crew from seized vessels.[71]
Beyond inter-state conflict, the Red Sea region is also shaped by non-traditional security threats, including piracy, illicit trafficking, and 'blue crime' – a convergence of arms smuggling, illegal fishing, and maritime terrorism within governance gaps.[72] Recent academic assessments highlight the role of 'shadow fleets', unregistered or covert vessels often linked to Iranian or Russian interests, which operate in the Red Sea to evade sanctions and transport illicit goods, including oil, weapons, and narcotics.[73] While international attention has largely focused on missile and drone attacks, scholars also warn of critical infrastructure vulnerabilities, including damage to undersea cables caused by bottom trawling and sabotage.[74]
A four color map of the Red Sea and its 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:
The Gulf of Suez is entirely bordered by Egypt.[75][76] The Gulf of Aqaba borders Egypt,Israel,Jordan and Saudi Arabia.[77][78]
In addition to the standard geographical definition of the six countries bordering the Red Sea cited above, areas such asSomalia 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 them.[79][80]
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