The Arabian Sea is a large marginal sea of the northern Indian Ocean situated between the Arabian Peninsula to the west and India and the broader South Asian region to the east. It covers approximately 3.9 million square kilometres and is one of the largest marginal seas in the world. Its northern waters extend toward Pakistan and Iran, while the western side is bordered by Oman and Yemen and the eastern side by India.
The Arabian Sea connects with the Gulf of Oman to the northwest and the Gulf of Aden to the southwest, while the Lakshadweep Sea and waters around the Indian subcontinent form part of its eastern and southeastern system. The sea has been central to maritime trade for thousands of years and remains important for shipping, fisheries, petroleum transport, offshore energy, monsoon systems, and regional climate.
The Arabian Sea is an important component of the Indian Ocean's physical system. Its waters are strongly influenced by the South Asian monsoon, which reverses direction seasonally and produces major changes in wind, surface circulation, temperature, and biological productivity. During the summer southwest monsoon, strong winds drive coastal upwelling along parts of the Arabian Peninsula and western India. Upwelling brings nutrient rich deeper water towards the surface, supporting large populations of phytoplankton and creating productive fisheries. During the winter northeast monsoon, atmospheric circulation changes and different patterns of mixing and productivity occur. The Arabian Sea is therefore one of the world's most significant examples of the interaction between seasonal atmospheric circulation and marine ecosystems.
The Arabian Sea has a complex surrounding geography. The Arabian Peninsula forms its western and southwestern boundary, with Oman and Yemen facing the sea directly. India forms much of the eastern boundary, while Pakistan lies along the northeastern coast. Iran borders the Gulf of Oman farther north, which connects the Arabian Sea to the Persian Gulf through the Strait of Hormuz. The Gulf of Aden connects the Arabian Sea to the Red Sea through the Bab el Mandeb. These waterways make the Arabian Sea an important junction between the Indian Ocean, Persian Gulf, Red Sea, East Africa, Arabian Peninsula, and South Asia.
Major rivers influence the Arabian Sea, particularly along the northern and eastern margins. The Indus River is the most important large river entering the Arabian Sea directly, forming a major delta along the coast of Pakistan. Rivers along India's western coast are generally smaller but contribute freshwater, sediments, nutrients, and pollutants. River discharge varies strongly with seasonal rainfall and monsoon conditions. The Indus Delta is an important coastal ecosystem containing mangroves, mudflats, tidal channels, and other habitats. Changes in freshwater availability, sediment supply, upstream water use, pollution, and sea level can therefore affect both the coastal environment and communities dependent on delta resources.
The Arabian Sea supports productive fisheries and diverse marine ecosystems. Seasonal upwelling provides nutrients that stimulate phytoplankton growth, which supports zooplankton, fish, seabirds, marine mammals, and other organisms. Important fisheries include sardines, mackerel, tuna, anchovies, and other species, although the composition and productivity vary geographically and seasonally. The sea also contains coral reefs, mangroves, seagrass habitats, deep sea ecosystems, and coastal wetlands. Marine productivity is affected by temperature, oxygen levels, nutrient availability, monsoon winds, currents, and climate variability. Human pressures include overfishing, plastic pollution, oil pollution, coastal development, shipping, nutrient enrichment, and climate change.
The Arabian Sea is an important global shipping region. Routes connect ports in South Asia and the Middle East with East Africa, Southeast Asia, Europe, and other parts of the world. Major ports around its shores include Mumbai and Mundra in India, Karachi and Port Qasim in Pakistan, Salalah and Duqm in Oman, and Aden near the Gulf of Aden. Energy transportation is particularly important because the Persian Gulf connects to the Arabian Sea through the Strait of Hormuz. Oil and liquefied natural gas transported from Gulf states frequently enter international maritime routes through the Arabian Sea. The sea therefore forms part of a global network linking energy producing regions with major consumer markets.
The Arabian Sea has a long maritime history. Seasonal monsoon winds made it possible for sailors to plan voyages between the Arabian Peninsula, East Africa, India, and Southeast Asia. Ancient and medieval merchants used predictable seasonal wind patterns to cross the sea, creating extensive networks of commercial and cultural exchange. Ports along the Arabian Sea participated in trade involving spices, textiles, metals, incense, pearls, grains, and many other commodities. Arab, Persian, Indian, African, and later European maritime traditions interacted across this region. The sea consequently played an important role in the development of coastal trading cities and in the spread of languages, religions, technologies, and cultural practices across the Indian Ocean world.
The Arabian Sea is also important to climate science because its monsoon driven circulation affects carbon cycling, oxygen distribution, rainfall systems, and marine productivity. The sea contains regions where oxygen concentrations are naturally low at intermediate depths, particularly within the broader Arabian Sea oxygen minimum zone. These low oxygen conditions influence which organisms can live at particular depths and affect biogeochemical cycles involving nitrogen and other elements. Climate change can alter sea temperatures, stratification, oxygen levels, productivity, and monsoon behaviour, although the magnitude and direction of individual changes depend on complex interactions among atmospheric, oceanic, and terrestrial processes.
