Arabian Sea

Geography

The Arabian Sea's surface area is about 3,862,000 km2 (1,491,130 sq mi). The maximum width of the sea is approximately 2,400 km (1,490 mi), and its maximum depth is 5,395 metres (17,700 ft). The largest river flowing into the sea is the Indus.

The sea has two main arms, the Gulf of Aden in the southwest, connecting it with the Red Sea through the strait of Bab-el-Mandeb; and the Gulf of Oman to the northwest, connecting it with the Persian Gulf. It also bounds the gulfs of Khambhat and Kutch on the Indian Coast, and the Laccadive Sea off the coast of southern India.

Limits

The only difference between the National Oceanic and Atmospheric Administration (NOAA) and International Hydrographic Organization (IHO) demarcations of the Arabian Sea is their determination of the sea's limit on its eastern border with India, disputing whether that be Devgad Island or Sadashivgad Village in Karnataka. According to NOAA, the demarcation of the sea is as follows: On the North and the East: From Cape Jiwani in Pakistan (25°1′10″N 61°44′15″E) eastward and southward, along the coasts of Pakistan and India, to Devgad Island (14°49′10″N 74°3′30″E), off the western coast of India; thence a line joining Devgad Island southwestward to Cora Divh (13°42′0″N 72°10′0″E) and thence southward, along the western side of the Lakshadweep and Maldives Islands, to the southern extremity of Addu Atoll (0°42′0″S 73°9′30″E)

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On the South: A line joining the southern extremity of Addu Atoll northwestward to Cape Hafun (10°26′0″N 51°25′0″E) in Somalia.

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On the West: From Cape Hafun northward, along the coast of Somalia, to Cape Asir [Guardafui] (11°50′0″N 51°17′0″E); thence a line joining Cape Asir northeastward to Cape Fartak (15°38′0″N 52°13′30″E) in Southern Yemen (the common limit with the Gulf of Aden [...] ), thence from Cape Fartak [...] northeastward, along the coasts of Southern Yemen and Oman, to Cape Al Hadd (22°32′0″N 59°47′30″E), in Oman; and thence a line joining Cape Al Hadd [...] northeastward to Cape Jiwani (25°1′10″N 61°44′15″E), in Pakistan (the common limit with the Gulf of Oman [...])

Hydrography

In 1959, the International Indian Ocean Expedition was among the first groups to conduct hydrographic surveys in the Arabian Sea. Additionally, "significant bathymetric surveys were also conducted by the Soviet Union during the 1960s".

The southern limits of the Sea are dominated by the Arabian Basin, which reaches depths of over 4,500 metres (14,764 ft), and which maintains a relatively constant depth throughout. The Carlsberg Ridge flanks the southern edge of the basin.

The deepest parts of the Arabian Sea sit in the Alula-Fartak Trough on its western border with the Gulf of Aden. The trough, which reaches depths of over 5,360 metres (17,585 ft), runs through both bodies. The deepest known point in the Arabian Sea sits at a depth of 5,395 metres (17,700 ft). Other significant deep points sit within the Arabian Basin, including a 5,358 m (17,579 ft) deep point off the northern limit of Calrsberg Ridge.

The continental shelf line is relatively narrow along the Makran, Arabian, and East African coastlines; conversely, its extends greatly from the coast of much of the Indian subcontinent, reaching distances exceeding 300 km (190 mi) in some places. The structure of the shelf line played a significant role in the creation of the Indus Fan, which was flooded and submerged along with the rest of the Indian coast at the end of the Last Glacial Maximum (LGM).

The Falaj Valley, discovered in 2009 by French surveyors, is an underwater valley off the eastern coast of Ash Sharqiyah Region in Oman. It is 81 kilometers wide, with a maximum depth of 3,097 metres (1.924 mi) and a relief of 1,151 m (3,776 ft), extending out roughly 75 km (47 mi) from the shelfline. It is named for the Falaj Irrigation System, a network of conduits, canals, and drainage systems built expansively across eastern Oman in the 5th century to equitably provision and maintain water supplies as groundwater sources depleted in that era.

The De Covilhăo Trough, discovered in 1930 and named for 15th century Portuguese explorer Pero de Covilhăo, reaches depths exceeding 4,400 metres (14,436 ft). It and the Murray Ridge on its western border separate the Indus Fan from the Oman Abyssal Plain, which leads on into the Gulf of Oman. The Murray Ridge arguably acts as an extension of the Owen fracture zone, an extensive bathymetric ridge running from the northwestern to southwestern Arabian Sea along a line roughly parallel to the southern Arabian and eastern Somalian coastlines, stretching from the central Makran coast to a point roughly 500 kilometres (310 mi) east of the central Somalian coastline. The fracture zone is the intersection point between the Indian and Arabian plates. The zone is characterized by steep slopes reaching heights of nearly 2,000 metres (6,600 ft) relative to the surrounding seabed. The fracture zone has acted as a natural barrier preventing sedimentation from the Indus Fan from extending out into the Oman Basin.

Islands

There are several islands in the Arabian Sea, all off the coast of major landmasses, with none at the sea's center. The most notable islands include the Socotra Archipelago, Masirah, and Astola, as well as the Lakshadweep and Maldives islands off the coast of India, contained within the Laccadive Sea.

Astola Island, also known as Jezira Haft Talar in Balochi, or 'Island of the Seven Hills', is a small, uninhabited island in the northern tip of the Arabian Sea in Pakistan's territorial waters. It is a nesting ground for several rare species, include hawksbill and green sea turtles.

Zalzala Koh off the coast of Pakistan only existed for a few years. The mud island was formed after the 2013 Balochistan earthquakes, but by 2016 had been completely submerged by the sea. The volcanic Error, Qalhat, and Wadia Guyots–southeast of the Socotra archipelago, east of the coast of Oman, and west off the coast of Karnataka, respectively–similarly sat above sea level at some point in their history.

Socotra, also spelled Soqotra, is the sea's largest island, part of an archipelago of four islands under Yemeni jurisdiction. It lies some 240 km (150 mi) east of the Horn of Africa and 380 km (240 mi) south of the Arabian Peninsula. The entire island is a UNESCO World Heritage Site, on account of its exceptional biodiversity, with "37% of Socotra’s 825 plant species, 90% of its reptile species and 95% of its land snail species [not occurring] anywhere else in the world". Many of these species are threatened or endangered.

Masirah and the five Khuriya Muriya Islands lie off the southeastern coast of Oman.

Climate and environment

Climate

The Arabian Sea experiences a monsoonal climate. Temperature patterns, precipitation levels, and recorded humidity levels are typically dependent upon the time of year and conditions to the sea's south and southwest. Despite the intensive rains which inundate the eastern edge of the basin annually, very little precipitation is witnessed on the sea's western shoreline, causing the region to constitute one of the driest seascapes on the planet.

Historically, minimum air temperatures of about 24 to 25 °C (75 to 77 °F) occurred between January and February, typically only exceeding 28 °C (82 °F) (via extension of the Indo-Pacific Warm Pool) between June and November. Most extreme surface temperatures typically occurred in the Persian Gulf; however, vacillating temperature extremes and dramatic meteorological events have become far more commonplace in recent years, producing significant fluctuations in this pattern.

Studies reviewing data up to the turn of the 3rd millennium indicate that sea surface temperature (SST) normals have increased by roughly 0.84 °C (~1.3–1.5 °F) on average over the past 100 years. The sea's all time minimum temperature occurred in 1975, its all-time maximum in 1998. Rapid warming from 1985 to 1987 was responsible for the prolonged pattern of increasingly warm air seen in the region today. Recent studies by the Indian Institute of Tropical Meteorology confirmed that the Arabian Sea is warming monotonously. Experts have consistently pointed to climate change and global and regional heating as playing a principal role in this trend.

The intensification and northward shift of the summer monsoon low-level jet over the Arabian Sea from 1979 to 2015 has led to increased upper ocean heat content, on account of enhanced downwelling and reduced southward heat transport. In much of the southeast Arabian Sea, the annual period during which Sea surface temperature normals exceeded 28 °C (82 °F) increased in length by roughly a month on average between 1982 and 2020. Indian oceanographers began recording SSTs exceeding 32 °C (90 °F) in localized areas of the same region as early as 2007. Moreover, 2024 stood as the hottest year in the Middle East on record, contributing to warming waters.

Starting in mid to late summer, strong southwesterly winds blowing from the Horn of Africa and western Indian Ocean carry warm, moist air northeastwards, contributing to strong oceanic forcing across the Arabian Basin. This forcing produces the prototypical rainy season of the South Asian monsoon cycle, alongside numerous additional annual environmental and meteorological shifts throughout the region. The winds produced during the southwest monsoon over the Arabian Sea, often referred to as the Findlater Jet, are heavily uniform northeastwards, and the strongest witnessed anywhere outside the Southern Ocean. The southwest monsoon is preceded by the Arabian Sea Mini Warm Pool (ASMWP), a period of 2 to 3 months prior to the beginning of the summer monsoon wherein SST averages exceeding 30 °C (86 °F) persist across much of southeastern basin. This gradual heating is reversed by mid-winter, when shallow, northeasterly winds carrying cool, dry air from the Hindu-Kush and Himalayas prevail.

Coastal and marine ecosystems

The Arabian Sea supports a diverse array of coastal and marine species, resulting from the extreme variability in climate and temperature seen within the basin, and the relative geographic isolation of its islands and the landmasses it borders from one another, producing distinct climactic and ecological conditions in different regions. Marine productivity in the Arabian Sea is highly variable throughout the year on account of the substantial difference in oceanic upwelling that takes place between different monsoonal regimes. The upwelling during the summer monsoon season, however, is the most intense to occur annually of any region on the planet.

The Arabian Sea large marine ecosystem (LME) is an ecological region encompassing an area of approximately 3,900,000 km2 (1,500,000 sq mi) within the sea, Gulf of Aden, and Gulf of Oman, principally below the continental shelf line, representing some coastal populations, and all populations of non-coastal marine life within the Arabian Basin. Though the Persian Gulf is included in this region as well, it may be excluded from certain analyses and accounts of the ecosystem, owing to the significant difference between its physical and hydrographic characteristics and those of the larger basin. In either case, the Arabian Sea LME remains one of the most ecologically productive regions on the planet, owing to the vast store of nutrients driven up to the sea's surface each year by intense oceanic upwelling in the fall and summer months.

The Arabian Sea LME is known to contain at least 330 species of coral, 550 species of mollusk, 200 species of crab, 24 species of marine mammal, and more than 1,200 species of fish. A significant number of marine mammals inhabiting the region are protected or listed as threatened by various international authorities. Among them are the blue whale, humpback whale (Stock D), killer whale, pygmy killer whale, finless porpoise, as well as various species of sperm whale and dolphin. As of 2026, 18 coastal regions in the Arabian Sea are listed by the Marine Mammals Protected Areas Task Force (MMPATF) as important marine mammal areas (IMMAs).

Despite its productivity, coastal pelagic fish populations in the region are relatively sparse, believed to be a result of unfavorable feeding conditions that discourage spawning of larvae. These conditions, in turn, are caused by incorrect mixing of the surface layer which results from the highly intense summer monsoon and the strong, current producing winds it creates in the sea's north and west.

History

The Arabian Sea trade

The Arabian Sea has served as an important route for and center of maritime trade since the development of early coastal sailing vessels in the Northern Indian Ocean and Southern Arabia in the 4th and 3rd millennia BC. Additionally, the sea and the lands surrounding it served as the central nexus of the Maritime Silk Road as it developed from the 2nd century BC onward. The trade led to the widespread migration and resettlement of various populations (coupled with a broader economic reordering of the coast and hinterland), the spread of pathogens and thus the instigation of various pandemics, the mass diffusion of ideas, technologies, and belief systems across the basin, and the joining of distant markets in goods, capital, and persons on the opposite ends of the Old World. Millet and sorghum, for instance, were introduced to the Indus Valley Civilization by means of the sea trade with East Africa. Most critical, though, was the maritime trade's role in facilitating the spread of Islam out from the Arabian Peninsula across the Indian Ocean to East Africa, South Asia, Southeast Asia, and the islands of the Malay Archipelago.

In the era of square rigged vessels, the Arabian Sea trade was effectively governed by the Northeast-Southwest Drift pattern of the northern Indian Monsoon Current. Northeasterly winds dominated in the summer months, allowing traders embarking from East Africa, the Horn of Africa, and the Arabian Peninsula to sail north and eastwards towards South Asia and the Bay of Bengal. Once there, early Arabian Sea traders were essentially trapped, marooned at their destination until the reversal and softening of the winds and ocean currents, which would enable them to sail home on calmer waters. This dynamic, combined with the desolate geography and inaccessibility of long stretches of the Arabian shoreline, made contact with one's point of origin before the beginning of the favorable monsoon regime effectively impossible. Sailors typically followed one of three "navigation circuits", all dependent upon local wind patterns to function. The first circuit rotated between the northern Red Sea and East Africa, the second from the Gulf of Aden to India, and the third from the Persian Gulf to either India or East Africa, with it being possible to finish all such journeys within a years time, potentially two, but never more. Routes during this period were thus heavily segmented, with sailors at each leg of the journey holding an effective monopoly on goods from markets in the east in the west, and vice versa.

The diffusion of the fore-and-aft rigged vessels into the Arabian Sea at the end of the 1st millennium CE changed the character of shipping in the Arabian Sea and across the wider Indian Ocean. The lateen sail originated in the Mediterranean in the latter part of the classical period and diffused into the Arabian Sea from there.

Modern economic and geopolitical activity

Petroleum and natural gas – shipping and production

A majority of the vast heavy oil and natural gas deposits in the Middle East are located at higher elevations in the Persian Gulf or inland north of the Arabian Basin. Major natural gas deposits, though, have been found on the sea's eastern edge off the coast of Western India. As a result of the former fact, traffic through the Strait of Hormuz on into the Arabian Sea accounts for roughly 25% of the global seaborne oil trade, transporting a majority of the crude oil exports of most Gulf nations. It accounts for 19% of seaborne LNG trade, representing more than 90% of the total LNG exports of Qatar and the United Arab Emirates. The vast majority of traffic, in both cases, is bound for Asia.

Commercial fishing and marine resource exploitation

Exploited marine species in the Arabian Sea include Indian oil sardines, typically caught off the west coast of India, and the drum and croaker fish of the family Sciaenidae. Most landing reports only indicate the catch as being 'marine fish', making a specific cataloguing of exploited species and variants difficult. Large oceanic pelagic fish are popular among commercial fishermen, otherwise. Bombay duck and anchovies are also harvested in significant quantities. Roughly half the market value of reported landings in the Arabian Sea can be attributed to perch- and herring-like species, with only a small quantity attributed to large marine species such as sharks and rays.

The Arabian Sea LME was one of the few large marine ecosystems to see little to no growth in commercial fishing yields from the 1990s to 2010s, reaching a settling point of roughly 2 million tonnes in 1990: This represented a quadrupling of fishing yields from 1950 onwards. Exploitation in the region has increased recently as a result of the intensive activity of Chinese industrial fishing vessels in the sea and wider Indian Ocean; these actions have been heavily scrutinized by Western and West and South Asian sources, among them, most notably, the governments of India and the United States. Trawl fishing operations are widespread within the Persian Gulf, in Oman, and across the Indian EEZ. Many nations on the Arabian coast suffer from extreme overcapacity in the fishing industry, having designed the market around large scale, industrial producers, at the expense of small-scale, relatively more sustainable local producers.

Recreational fishing is popular in the Sultanate of Oman.

Major ports and naval installations

Oil makes up a significant proportion of the commercial traffic handled by ports in the Arabian Sea, particularly in its north and east. Eastern ports have seen a marked uptick in activity since the start of the 2026 Iran War.

Jawaharlal Nehru Port in Mumbai is the largest port in the Arabian Sea, and the largest container port in India. In 2017, the port suffered a major cyberattack targeting the operations of Danish shipping giant Maersk. Other major Indian ports of the Arabian Sea include the Port of Mumbai (Maharashtra), Mundra, Kandla and Pipavav Ports (Gujarat), and Mormugão Port (Goa).

The Port of Karachi is Pakistan's largest and busiest seaport, located on the country's southeastern coast. It is situated between the Karachi towns of Kiamari and Saddar. Gwadar Port is a warm-water, deep-sea port situated at Gwadar in Balochistan at the apex of the Arabian Sea near the entrance to the Persian Gulf, about 460 km west of Karachi, and approximately 75 km (47 mi) east of Pakistan's border with Iran. The port is located on the eastern bay of a natural hammerhead-shaped peninsula jutting into the Arabian Sea from the coastline. 280 km east along the coast at Ormara sits Jinnah Naval Base, the country's second largest naval base, which is situated on a similarly shaped tombolo jutting into the Arabian.

Oman is home to a variety of foreign military installations which provide auxiliary and support services to friendly vessels and crew. In the 2010s, the Port of Salalah in the country's south hosted personnel from a joint international task force combatting piracy in the Arabian Sea. The port has seen a decline in traffic in recent years owing to attacks by Yemeni Houthi rebels. The British-Omani Duqm Naval Dockyard provides repair and maintenance services to vessels of friendly nations. Additional facilities are operated by the United States Air Force on Masirah Island.

The Port of Nishtoun is the only major Yemeni port facing the Arabian Sea, located on the country's far eastern coast near the border with Oman. Nishtoun is used as a coordination site between Yemeni merchants and regional trading partners in the Gulf, while fishing accounts for most of its annual stationary functions. In December 2025, the port was seized by forces of the U.A.E-backed Southern Transitional Council (STC), prior to its collapse in January of the following year.