Red Sea

The Red Sea is a narrow inland extension of the Indian Ocean, nestled between the northeastern coast of Africa and the Arabian Peninsula. At its northern end it bifurcates into two gulfs: the Gulf of Suez to the northwest, which connects — via the Suez Canal — to the Mediterranean Sea, and the Gulf of Aqaba to the northeast, which borders Saudi Arabia, Jordan, Israel, and Egypt. At its southern end the Red Sea narrows dramatically into the Bab-el-Mandeb Strait before opening into the Gulf of Aden and the broader Indian Ocean. This geography makes the Red Sea one of the most strategically important bodies of water on Earth.

As a maritime trade corridor, the Red Sea is indispensable to global commerce. Approximately 12–15% of global trade and 8–10% of all seaborne trade transits these waters each year, primarily between Asia and Europe. Bulk carriers laden with grain and minerals, supertankers carrying Persian Gulf crude, and container ships stacked high with manufactured goods make this route their highway. The Suez Canal, completed in 1869 under Ferdinand de Lesseps, transformed the Red Sea from a secondary sea into the arterial core of world trade, eliminating the need for vessels to sail around the Cape of Good Hope and shortening the Europe–Asia shipping distance by approximately 7,000 km.

Beyond its commercial role, the Red Sea is oceanographically remarkable. No rivers drain into it — making it the only major marginal sea in the world without significant freshwater input — and evaporation far exceeds precipitation, producing salinity values of 36–41 parts per thousand that rival the Dead Sea in some northern reaches. The sea sits atop an active rift zone still pulling apart at approximately 1.6 centimetres per year. Despite these extreme conditions, the Red Sea supports some of the world's most biodiverse and heat-resilient coral reef ecosystems, attracting scientists studying marine adaptation to climate change. For the mariner, the Red Sea presents a spectrum of challenges: oppressive summer heat, sandstorms materialising without warning, short steep seas driven by relentless northwest winds, demanding pilotage in the Gulf of Suez, and since late 2023, the very real threat of missile and drone attacks from Houthi forces in Yemen.

Geography & Physical Characteristics

The Red Sea occupies an elongated basin stretching approximately 1,930 km from the Suez Canal in the north to the Bab-el-Mandeb Strait in the south. At its widest point it spans roughly 355 km, though it narrows to just 29 km at the strait itself. The total surface area is approximately 438,000 km², with a maximum depth of 3,040 m recorded in a trench off Port Sudan and an average depth of 491 m. Coordinates of the geographic centre approximate 22°N 38°E.

The Red Sea is a product of continental rifting. It sits atop the Red Sea Rift — part of the broader East African Rift System — where the African and Arabian tectonic plates are separating at a rate of approximately 1.6 cm per year. Over geological time this spreading will eventually widen the Red Sea into a full ocean, much as the Atlantic formed from the splitting of Pangaea. This rift origin explains the characteristic narrow, elongated shape of the sea and its relatively young seafloor. Two notable bathymetric features of scientific interest are the Kebrit Deep and the Atlantis II Deep, the latter containing extremely hot brines (up to 68°C) and metallic sediments enriched in gold, silver, zinc, and copper — resources that have attracted commercial interest in deep-sea mining proposals.

The northwestern arm of the Red Sea is the Gulf of Suez — approximately 300 km long but generally shallow, with depths mostly between 30 and 80 m. This shallowness, combined with oil platforms, strong tidal currents, and heavy traffic, makes Gulf of Suez navigation technically demanding. Mandatory pilotage applies for most commercial vessel categories. The northeastern arm is the Gulf of Aqaba, strikingly different in character: extremely deep (up to 1,800 m) and narrow, with steep walls that plunge from desert mountains directly into the sea. Aqaba (Jordan) and Eilat (Israel) sit at its northern tip, making them unusual examples of landlocked countries with Red Sea access.

The Bab-el-Mandeb Strait — Arabic for "Gate of Grief" — forms the southern gateway. The strait is approximately 30 km wide at its narrowest point, but the presence of Dact-al-Mayun Island (also known as Perim Island) divides it into two navigable channels: the eastern channel (3 km wide) used by most commercial traffic, and the larger western channel (26 km wide). The Sinai Peninsula forms a distinctive triangular landmass separating the Gulf of Suez from the Gulf of Aqaba, its stark desert mountains rising to 2,637 m at Mount Catherine. Island groups of navigational significance include the Dahlak Archipelago off the Eritrean coast — a labyrinth of some 350 islands and islets — and the Farasan Islands off the Saudi Arabian coast, both requiring careful chart work due to extensive shoals.

Oceanography & Climate

The Red Sea climate is governed by its position between two arid landmasses — the Sahara and Arabian deserts. Air temperatures in summer can reach 40–50°C in the northern Red Sea, while sea surface temperatures (SST) in August routinely measure 32–34°C — among the highest open-sea surface temperatures anywhere on Earth. In winter the northern Red Sea cools to 17–22°C while the south remains a relatively constant 26–28°C year-round.

The most distinctive oceanographic feature of the Red Sea is its salinity regime. With no river inflow and an annual evaporation exceeding precipitation by approximately 2 metres, salt concentrations build continuously. Surface salinity varies from about 36 ppt near the Bab-el-Mandeb — where less-saline Indian Ocean water flows in — to 41 ppt or more in the northern Gulf of Suez. This anti-estuarine circulation pattern sees relatively fresh Indian Ocean surface water flow northward into the Red Sea, while dense, hot, hypersaline deep water flows southward at depth and exits into the Gulf of Aden, sinking to form a distinctive water mass detectable in the Indian Ocean.

Wind patterns create a complex regime that mariners must understand well. In the northern Red Sea, a persistent northwest wind (known locally as the Shamal when originating from the Arabian Peninsula) blows throughout most of the year, generating rough conditions for northbound vessels. In the southern Red Sea, winds are more seasonal: northerly in summer, more variable in winter. Around latitude 20°N the two wind systems converge, creating a confused sea state with cross-swells — a zone where short, steep, unpredictable waves make vessels roll heavily. Seasonal monsoon influences penetrate through the Bab-el-Mandeb: the southwest monsoon between June and September drives stronger currents into the Red Sea, while the northeast monsoon in winter partially reverses surface currents near the strait.

Dust storms — known as Haboob when originating from the Sudanese and Saudi interior — represent one of the most dramatic navigational hazards. A Haboob can reduce visibility from 10 km to zero in under 30 minutes, coating decks in fine orange-red sand and clogging air filters. Simultaneously, the extreme heat creates temperature inversions that cause radar ducting: radio energy from the ship's radar bends along the temperature boundary, producing false echo returns and apparent "ghost targets" on the radar display. Mirage effects over the flat, superheated sea surface can cause optical distortions, making land and vessels appear to float above the horizon. Tidal ranges in the Red Sea are relatively modest — typically 0.5–1.0 m at most locations — but tidal currents at Bab-el-Mandeb can reach 2–3 knots and must be factored into passage planning.

Marine Ecology & Biodiversity

Despite — or perhaps because of — its extreme physical environment, the Red Sea hosts one of the world's most remarkable marine ecosystems. The coral reef systems that fringe much of the coastline have evolved under conditions of chronically warm water, high salinity, and intense ultraviolet radiation, producing organisms with exceptional physiological resilience. Scientists regard Red Sea corals as among the most thermally tolerant on the planet: while corals elsewhere bleach and die when water temperatures rise just 1–2°C above seasonal norms, many Red Sea coral species can withstand temperatures 5°C or more above their historical baseline without bleaching. This has made them the subject of intensive research into mechanisms of thermal adaptation, and a potential source of hardy coral larvae for reef restoration programmes in the Caribbean, Indian Ocean, and Pacific.

The Red Sea supports approximately 1,200 fish species, of which an extraordinary 44% are endemic — found nowhere else in the world. This endemism reflects the sea's geological isolation: access to the broader Indian Ocean through the shallow Bab-el-Mandeb has historically restricted the mixing of fish populations, allowing unique evolutionary trajectories. Notable endemic fish include the Picasso triggerfish (Rhinecanthus assasi) and numerous parrotfish, wrasse, and damselfish species. Larger marine fauna include dugongs (Dugong dugon) — found particularly along the Egyptian and Saudi coasts — bottlenose and spinner dolphins, pods of minke whales, and occasional blue and sperm whales in deeper waters near the Bab-el-Mandeb. Whale sharks aggregate seasonally in southern Red Sea waters and in the Djibouti region to feed on coral spawn slicks, attracting research and dive tourism.

Hawksbill (Eretmochelys imbricata) and green sea turtles (Chelonia mydas) nest on remote beaches across Eritrea, Sudan, Saudi Arabia, and Egypt, with several important rookeries located on the Farasan Islands and the Sudanese coast. Mangrove forests — while sparse compared to other tropical seas — occur along parts of the Eritrean, Sudanese, and Saudi coastlines, providing critical nursery habitat for fish and crustaceans. Seagrass beds of Halophila stipulacea and Thalassia hemprichii support dugong foraging grounds. The exceptional water clarity of the Red Sea — with visibility of 30–40 m in undisturbed reef areas — is a direct consequence of the absence of riverine sediment input. Marine protected areas include Ras Muhammad National Park at the tip of the Sinai Peninsula in Egypt, one of the world's most celebrated diving destinations, and increasingly ambitious conservation zones within Saudi Arabia's NEOM mega-project development area on the northern Red Sea coast.

Despite this richness, the Red Sea's ecosystem faces significant pressures. Major bleaching events occurred in 1998 and 2015, though the degree of mortality was lower than in comparable events in the Indian Ocean and Pacific. Coastal development, particularly large-scale tourism and industrial projects in Saudi Arabia and Egypt, has resulted in localised reef destruction through dredging, sedimentation, and anchor damage. Illegal fishing by foreign-flagged vessels operating without licences depletes stocks, particularly in Eritrean and Sudanese waters where surveillance is limited.

Maritime Trade Routes & Shipping

The Red Sea's importance to global shipping cannot be overstated. Approximately 22,000 vessels transited the Suez Canal in 2022, generating record revenues of approximately $9.4 billion for the Suez Canal Authority. The canal links the Mediterranean Sea to the Red Sea — and through it to the Indian Ocean and beyond — handling roughly 12–15% of world trade by value, including a large proportion of containerised goods, crude oil, refined petroleum products, LNG, dry bulk commodities, and vehicle carriers.

The Bab-el-Mandeb Strait is the second most critical oil chokepoint in the world after the Strait of Hormuz. Approximately 4.8 million barrels of crude oil and petroleum products pass through it each day, representing a substantial share of global seaborne oil trade. The strait is also traversed by LNG tankers from Qatar's Ras Laffan terminal destined for European markets, and by VLCC supertankers loading crude at Saudi Aramco's Yanbu and Jubail terminals. Any disruption at Bab-el-Mandeb forces tankers onto the much longer Cape of Good Hope route around southern Africa — adding approximately 10–14 days and 3,500–4,000 nautical miles to the voyage, with fuel cost increases of $1 million or more per transit.

The Ever Given grounding in the Suez Canal in March 2021 provided a dramatic demonstration of this vulnerability. The 400-metre-long container vessel became diagonally lodged in the 200-metre-wide canal for six days, blocking an estimated $9.6 billion of trade per day. The incident triggered immediate diversions of hundreds of vessels around the Cape of Good Hope and exposed the fragility of global just-in-time supply chains to a single chokepoint failure.

Traffic in the Red Sea broadly divides by direction. Northbound convoys carry Asian manufactured goods — electronics, clothing, vehicles, machinery — in containers, along with LNG tankers from Qatar, chemical tankers from Persian Gulf ports, and bulk carriers loaded with Indian coal and grain. Southbound convoys carry European grain, bulk commodities including coal and potash from Jordan, vehicles from European factories destined for Asian markets, and empty containers returning to Asian manufacturers. Saudi Arabia's Vision 2030 programme, which aims to transform the kingdom into a major logistics and industrial hub, is expected to substantially increase Red Sea cargo volumes through ports such as Jeddah, Yanbu, and the new King Salman International Airport project near NEOM.

All major global container carriers operate services through the Red Sea and Suez Canal, including Maersk, MSC Mediterranean Shipping Company, CMA CGM, Hapag-Lloyd, COSCO Shipping, and Evergreen. These operators maintain regular rotation schedules linking Asia to North Europe and the Mediterranean via weekly sailings, making the Red Sea the cornerstone of the Asia-Europe trade lane — the world's busiest container route by volume.

Key Ports & Harbours

The Red Sea is served by a number of significant commercial ports spread across eight coastal nations. Understanding the characteristics and specialist functions of each is essential for mariners engaged in Red Sea trade.

Jeddah Islamic Port — Saudi Arabia

The largest port on the Red Sea and one of the Middle East's busiest, Jeddah Islamic Port handles over 5 million TEU (twenty-foot equivalent units) of container traffic annually, along with substantial general cargo, Ro-Ro (roll-on roll-off vehicle) traffic, and bulk commodities. Situated on Saudi Arabia's Hejaz coast at approximately 21°N, it serves as the principal gateway for imports to the kingdom and as a transshipment hub for regional distribution. The port is managed by the Saudi Ports Authority (Mawani) and operates around the clock. Access requires compulsory pilotage; the port has its own VTS and communicates on VHF Channel 16 and working channels as directed.

Port Sudan — Sudan

Sudan's principal — and effectively only major — seaport, Port Sudan handles the nation's export commodities including gum arabic (of which Sudan is the world's largest producer), sorghum, sesame, groundnuts, and cotton. It also serves as an import gateway for fuel and food commodities. Located on a sheltered natural harbour, Port Sudan has been affected by periodic political instability. The port is subject to mandatory pilotage and operates under the Sudan Sea Ports Corporation. Vessels must obtain a berth allocation well in advance; delays are common due to limited berth availability and cargo handling infrastructure.

Port of Aqaba — Jordan

Jordan's only seaport and its sole access to the sea, Aqaba sits at the northern tip of the Gulf of Aqaba. The port is the primary export point for Jordanian potash — one of the country's most significant revenue earners — and phosphate rock, loaded at the specialised bulk terminal of the Arab Potash Company. The port also handles general cargo, Ro-Ro traffic, and has a dedicated cruise terminal serving travellers visiting Petra and Wadi Rum. Navigation in the Gulf of Aqaba requires careful attention to Israeli naval exercise areas and restricted zones near Eilat to the north.

Yanbu Industrial Port — Saudi Arabia

Yanbu, located on Saudi Arabia's western coast approximately 300 km north of Jeddah, is a purpose-built industrial port complex serving the Yanbu Industrial City. It handles crude oil exports from the western end of the East-West Pipeline (connecting Saudi Aramco's Abqaiq facilities to the Red Sea), refined petroleum products from the large YASREF refinery complex, petrochemicals, and related industrial cargoes. Yanbu's significance as an oil terminal makes it a critical facility in global energy logistics.

Safaga — Egypt

Located on Egypt's Red Sea coast approximately 60 km south of Hurghada, Safaga is Egypt's principal Red Sea commercial port. It specialises in the export of phosphate rock from the vast mineral deposits of the Eastern Desert, loaded via dedicated conveyor systems. Safaga also operates a regular Ro-Ro and passenger ferry service to Duba on the Saudi coast, used by Egyptian workers and pilgrims travelling to Mecca and Medina. The port lies close to dive tourism centres but handles primarily bulk and ferry traffic.

Port of Suez — Egypt

Situated at the southern entrance of the Suez Canal at the northern end of the Gulf of Suez, the Port of Suez (also known as Port Ibrahim or Port Tewfik at the canal entrance) is the gateway between the Red Sea and the canal. While not a major cargo port in its own right — most cargo is handled at Port Said on the Mediterranean end — Suez plays a critical role in canal logistics: vessel inspections, convoy assembly, pilot boarding and disembarkation, and emergency services. All vessels transiting the canal must comply with Suez Canal Authority regulations regarding pilotage, searchlight requirements, and pre-transit documentation.

Historical & Strategic Significance

The Red Sea's role as a maritime highway predates recorded history. Ancient Egyptian expeditions to the mysterious land of Punt — believed to have been located somewhere along the Eritrean, Somali, or Yemeni coast — were conducted via the Red Sea as early as 2500 BCE, with the celebrated expedition of Queen Hatshepsut around 1470 BCE depicted in detailed relief carvings at Deir el-Bahari. These voyages brought back incense, myrrh, ebony, and exotic animals. For millennia, dhow traders from Arabia, India, and East Africa criss-crossed the Red Sea and Indian Ocean, exploiting the seasonal monsoon winds to carry cotton, spices, ivory, and slaves.

The sixteenth century brought European ambitions to control this strategic waterway. Following Vasco da Gama's rounding of the Cape of Good Hope in 1498, the Portuguese attempted to establish dominance over Indian Ocean trade routes by force, attempting to blockade the Red Sea entrance at Bab-el-Mandeb. Their failure to take Aden permanently — repulsed by Ottoman forces in 1513 and 1517 — left the Red Sea in Ottoman hands for the next three centuries, generating enormous revenues from the spice trade transiting Alexandria to Venice. The Ottoman hold on the Red Sea was one reason European powers invested so heavily in developing the Cape of Good Hope route.

The opening of the Suez Canal on 17 November 1869 under the entrepreneurial vision of Ferdinand de Lesseps fundamentally restructured global trade. The canal reduced the voyage from London to Bombay by approximately 7,000 km and transformed the Red Sea from a secondary regional sea into the world's most important maritime transit corridor overnight. Control of the canal became a paramount geopolitical objective: Britain purchased a controlling stake in the Suez Canal Company in 1875, and the canal remained under Anglo-French control until the Suez Crisis of 1956. Egyptian President Gamal Abdel Nasser's nationalisation of the canal in July 1956 triggered the invasion by Israel, Britain, and France — a military adventure that ended in a humiliating withdrawal under American and Soviet pressure and marked the final collapse of European imperial dominance in the Middle East.

The Six-Day War of June 1967 between Israel and Arab states resulted in the closure of the Suez Canal for eight years — from June 1967 to June 1975. Fourteen vessels caught inside the canal at the outbreak of hostilities were trapped in the Great Bitter Lake, unable to proceed in either direction as the shores became front lines. These ships — from Britain, France, West Germany, the United States, Sweden, Poland, Czechoslovakia, and Bulgaria — became known as the "Yellow Fleet" because desert sand progressively covered their hulls. Their crews maintained a remarkable community in isolation, organising sporting events and postal services, before the ships were finally freed and towed — many no longer seaworthy — when the canal reopened. The closure forced a generation of tanker design toward much larger vessels capable of economically rounding the Cape of Good Hope, giving birth to the VLCC era.

From late 2023, the Red Sea re-emerged as a global security flashpoint. Houthi forces controlling much of northwestern Yemen began launching ballistic missiles, anti-ship cruise missiles, and unmanned aerial and surface vessels at commercial shipping in the Red Sea and Gulf of Aden, claiming solidarity with Gaza in the Israel-Hamas conflict. The attacks forced major container carriers including Maersk, MSC, Hapag-Lloyd, and CMA CGM to suspend Red Sea operations and reroute via the Cape of Good Hope, adding 10–14 days and approximately $1 million in additional fuel costs per round trip. Container freight rates tripled within weeks. A US-led multinational naval coalition — Operation Prosperity Guardian — was deployed to defend commercial shipping, with warships including USS Carney, HMS Diamond, and multiple European frigates conducting interceptions of Houthi drones and missiles. The crisis underscored the acute vulnerability of global supply chains to disruption of this single maritime chokepoint.

Navigation Safety & Hazards for Mariners

The Red Sea falls within NAVAREA IX, administered by India, and mariners should monitor NAVAREA IX navigational warnings (broadcast on Inmarsat-C SafetyNET and NAVTEX) when transiting the area. As of 2023–2024, NAVAREA IX warnings have frequently included military exercise areas, wreck positions, and specific security advisories related to the Houthi conflict.

Thermal hazards represent a persistent operational challenge, particularly in summer. Air temperatures exceeding 45°C in the northern Red Sea impose significant physiological stress on deck crews conducting cargo operations, maintenance, and watchkeeping. Engine room temperatures can exceed 50°C with ambient seawater temperatures severely limiting the cooling efficiency of sea water cooling systems. Masters should ensure crew are rotated through work schedules to prevent heat exhaustion, that potable water consumption is maximised, and that PPE requirements are adjusted for extreme heat. Machinery manufacturers' temperature tolerances for key components should be verified against expected conditions. Air conditioning failures in this environment can rapidly become life-threatening.

Sandstorms (Haboob) constitute one of the most rapidly developing hazards. A sandstorm originating in the Sudanese or Saudi interior can arrive at a vessel with little warning, reducing visibility from unlimited to effectively zero in under 30 minutes. Prudent mariners monitor synoptic and satellite imagery for developing dust events, establish a radar watch, reduce speed in accordance with COLREG Rule 6 (Safe Speed), sound fog signals as required under COLREG Rule 35, and obtain frequent GPS position fixes before the GPS signal may degrade in heavy dust. All air intakes, including those for main engines, generators, and HVAC systems, should be monitored for clogging. After a Haboob, a thorough inspection of radar antenna waveguides and external equipment is recommended.

Radar ducting and mirage effects are particularly prevalent in the northern Red Sea during summer. Temperature inversions created when hot, dry air overlies the relatively cooler sea surface cause radio waves to bend along the atmospheric boundary, potentially extending radar range far beyond normal but also creating false echoes and obscuring real targets in shadow zones. Officers should be alert to apparently stationary radar targets that may be anomalous propagation returns, and cross-reference all radar contacts with AIS data and visual observation.

The Gulf of Suez requires particular navigational caution. The mandatory pilotage area begins at a defined boarding position at either the northern or southern entrance, and no vessel above the applicable GT threshold may proceed without an authorised Suez Canal Authority pilot aboard. The channel is congested with northbound and southbound convoy traffic, restricted by numerous oil and gas production platforms — particularly in the northern section — and characterised by strong cross-tidal currents at certain states of tide. At night, the multiplicity of platform lights, navigation buoys, and vessel lights demands meticulous radar watchkeeping. Depths in parts of the Gulf of Suez shoal dramatically outside the dredged channel.

The Bab-el-Mandeb Strait maintains Traffic Separation Schemes (TSS) that mariners must follow in accordance with COLREG Rule 10. Vessels transiting the strait are required to report to Yemen Coastguard Radio on VHF Channel 16 — though since the onset of the Houthi conflict, this reporting arrangement has been disrupted. The US and UK governments have issued formal advisories to mariners recommending registration with the United Kingdom Maritime Trade Operations (UKMTO) organisation based in Dubai, which coordinates reporting from vessels transiting the area and relays security threat information. Vessels transiting the Red Sea and Gulf of Aden during the period of elevated threat should consult the latest guidance from IMO MSC Circulars, UKMTO, and the Maritime Security Centre — Horn of Africa (MSCHOA) website.

Security precautions for vessels that do transit during the Houthi threat period include: registering with UKMTO; maintaining maximum speed; keeping a 24-hour armed watch if permitted by flag state; activating AIS and maintaining it active; keeping accommodation spaces sealed against possible boarding attempts; conducting regular drills; and monitoring GMDSS broadcasts for up-to-date threat assessments. The BIMCO, IMO, and flag state administrations of most major maritime nations have issued specific guidance. Some flag states have advised against transit altogether.

UKHO Admiralty charts covering the Red Sea include NP64 (Red Sea Pilot), and relevant charts from the 4700-series. Mariners should ensure charts are updated to the latest edition and incorporate all relevant Temporary and Preliminary Notices to Mariners. The UKHO has been active in issuing T&P NMs related to the Houthi conflict including new prohibited areas and recommended routing measures.

Environmental Issues

The Red Sea faces an array of environmental pressures, many directly attributable to its role as a major shipping lane. The combination of high tanker traffic, proximity of shipping lanes to coral reefs, and limited capacity for self-dilution in a semi-enclosed sea creates conditions where oil spill events can be catastrophic. The Red Sea, Gulf of Aden, and Gulf of Oman collectively form part of the ROPME (Regional Organisation for the Protection of the Marine Environment) Sea Area, designated under MARPOL Annex I as a Special Area — meaning even tighter restrictions on operational discharges of oil than apply on the open ocean. Vessels operating in this Special Area are prohibited from discharging bilge water containing more than 15 ppm oil content.

Desalination plants represent an often-overlooked source of marine pollution. Saudi Arabia operates some of the largest seawater desalination capacity in the world, with major facilities at Yanbu, Jeddah, Rabigh, and Dhuba on the Red Sea coast. These plants return concentrated brine — hypersaline reject water — to the sea at rates and concentrations that significantly exceed the ambient salinity in discharge zones, creating localised dead zones where benthic organisms cannot survive. The discharge of warm, chlorinated brine also affects seagrass beds and coral communities near outfall pipes. As Saudi Arabia and other Red Sea nations expand their desalination capacity under growing freshwater demand, the cumulative impact on Red Sea marine ecosystems is a growing concern for environmental scientists.

Plastic pollution in the Red Sea reflects the broader global crisis but is complicated by the semi-enclosed geography which limits exchange of surface waters. Plastic debris entering from land-based sources — inadequately managed waste in coastal cities and from rivers in the broader catchment draining via Bab-el-Mandeb — accumulates in gyres and washes up on remote beaches. Microplastic contamination has been documented in Red Sea fish species and in coral mucus. MARPOL Annex V prohibits the discharge of all garbage, including plastics, from ships anywhere at sea, and Special Area regulations apply in the Red Sea.

Mining operations in Sudan — both artisanal gold mining and legacy industrial mineral extraction — contribute heavy metal contamination (mercury, arsenic, lead) to Red Sea coastal waters via seasonal wadis (dry riverbeds that flow briefly after rare rains). The Atlantis II Deep metallic sediment deposit has attracted commercial interest from several companies seeking to mine its extraordinarily rich ore reserves, raising significant questions about potential plume contamination of the water column if large-scale extraction were to proceed.

Climate change poses the most systemic long-term threat. The Red Sea is warming at a rate slightly above the global ocean average, driven by a combination of global temperature rise and regional land-use changes. While Red Sea corals have shown greater resilience than many counterparts elsewhere, major bleaching events occurred in 1998 (following the global El Niño event) and again in 2015. Continued warming at projected rates — with sea surface temperatures potentially rising a further 1.5–2°C by 2100 — will eventually exceed even the adaptation limits of Red Sea corals. Sea level rise threatens low-lying coastal settlements and infrastructure along the Eritrean and Yemeni coasts in particular. Changing monsoon patterns may alter the current regime at Bab-el-Mandeb, with potential consequences for deep-water circulation and oxygen levels in the deeper basins.