The Persian Gulf has many fishing grounds, extensive reefs (mostly rocky, but also coral), and abundant pearl oysters, however its ecology has been damaged by industrialization and oil spills.

[2] The current flooding of the basin started 15,000 years ago due to rising sea levels of the Holocene glacial retreat.

[4] This inland sea of some 251,000 square kilometres (96,912 sq mi) is connected to the Gulf of Oman in the east by the Strait of Hormuz; and its western end is marked by the major river delta of the Shatt al-Arab, which carries the waters of the Euphrates and the Tigris.

Persian Gulf islands are often also historically significant, having been used in the past by colonial powers such as the Portuguese and the British in their trade or as acquisitions for their empires.

Writing the water balance budget for the Persian Gulf, the inputs are river discharges from Iran and Iraq (estimated to be 2,000 cubic metres (71,000 cu ft) per second), as well as precipitation over the sea which is around 180 mm (7.1 in)/year in Qeshm Island.

The evaporation of the sea is high, so that after considering river discharge and rain contributions, there is still a deficit of 416 cubic kilometres (100 cu mi) per year.

[12] In the book of Nearchus known as Indikê (300 BC), the word "Persikon kolpos" is mentioned for multiple times meaning "Persian gulf".

In the second century the Lakhum tribe, who lived in what is now Yemen, migrated north and founded the Lakhmid Kingdom along the southern coast.

Siraf, was also significant in that it had a flourishing commercial trade with China by the fourth century, having first established connection with the far east in 185 AD.

Following the arrival of the English and the Dutch, the Safavid Empire allied with the newcomers to contest Portuguese dominance of the seas in the 17th century.

[37]Portuguese expansion into the Indian Ocean in the early 16th century following Vasco da Gama's voyages of exploration saw them battle the Ottomans up the coast of the Persian Gulf.

In 1521, a Portuguese force led by commander Antonio Correia invaded Bahrain to take control of the wealth created by its pearl industry.

The Persian Gulf was therefore opened to a flourishing commerce with the Portuguese, Dutch, French, Spanish and the British merchants, who were granted particular privileges.

[42] In World War II, the Western Allies used Iran as a conduit to transport military and industrial supply to the USSR, through a pathway known historically as the "Persian Corridor".

Britain utilized the Persian Gulf as the entry point for the supply chain in order to make use of the Trans-Iranian Railway.

[43] The Persian Gulf therefore became a critical maritime path through which the Allies transported equipment to Soviet Union against the Nazi invasion.

[49][50] In 2018, the UK opened a permanent military base, HMS Jufair, in the Persian Gulf, the first since it withdrew from East of Suez in 1971 and is developing a support facility in Oman.

[51][52][53] Eight nations have coasts along the Persian Gulf: Bahrain, Iran, Iraq, Kuwait, Oman, Qatar, Saudi Arabia, and the United Arab Emirates.

[59] Along with Bryde's whales,[60][61][62][63] these once common residents can still can be seen in deeper marginal seas such as Gulf of Aden,[64] Israel coasts,[65] and in the Strait of Hormuz.

In 2017, waters of the Persian Gulf along Abu Dhabi were revealed to hold the world's largest population of Indo-Pacific humpbacked dolphins.

Also called "sea cows", for their grazing habits and mild manner resembling livestock, dugongs have a life expectancy similar to that of humans and they can grow up to 3 metres (9.8 feet) in length.

[78][79] Ambitious and uncalculated construction schemes, political unrest, ever-present international conflict, the most lucrative world supply of oil, and the lack of cooperation between Arab states and Iran, have had a negative impact on the survival of many marine species, including dugongs.

Concerns regarding the endangerment of the kalbaensis subspecies of the collared kingfishers were raised by conservationists over real estate development by the United Arab Emirates and Oman.

A UN plan to protect the mangroves as a biological reserve was ignored by the emirate of Sharjah, which allowed the dredging of a channel that bisects the wetland and construction of an adjacent concrete walkway.

[80] Real estate development in the Persian Gulf by the United Arab Emirates and Oman also raised concerns that habitats of species such as the hawksbill turtle, greater flamingo, and booted warbler may be destroyed.

Recent statistics and observations show that dolphins are at danger of entrapment in purse seine fishing nets and exposure to chemical pollutants; perhaps the most alarming sign is the "mass suicides" committed by dolphins off Iran's Hormozgan province, which are not well understood, but are suspected to be linked with a deteriorating marine environment from water pollution from oil, sewage, and industrial run offs.

Recent years have seen a drastic decline in the coral population in the Persian Gulf, partially owing to global warming but mostly to irresponsible dumping by Arab states like the UAE and Bahrain.

[80] Mangroves are a diverse group of shrubs and trees belonging to the genus Avicennia or Rhizophora that flourish in the salt water shallows of the Persian Gulf, and are the most important habitats for small crustaceans that dwell in them.

The Persian Gulf and its coastal areas are the world's largest single source of petroleum,[91] and related industries dominate the region.