The Persian Gulf, an arm of the Arabian Sea, south-western Asia, between the Arabian Peninsula on the south-west and Iran on the north-east. The gulf extends north-west about 965 km (600 mi) from the Strait of Hormuz to Shatt Al Arab, a river formed by the confluence of the Tigris and Euphrates rivers. The gulf is connected to the Arabian Sea by the Strait of Hormuz and the Gulf of Oman. The Persian Gulf varies in width from 47 to 370 km (29 to 230 mi). The area is about 233,000 sq km (90,000 sq mi) and the greatest depth is about 90 m (300 ft). The chief islands in the gulf are Qeshm and Bahrain. The United Arab Emirates, Saudi Arabia, Qatar, and Kuwait are on the south-western shore; Iraq is on the northern tip, and Iran is on the north-eastern shore (see Persian Gulf States).
The Iranian shore tends to be mountainous and fringed with cliffs, white sandy beaches border the Arabian shore, broken by many small islands and lagoons. Large banks of pearl-producing mollusks are found on the Arabian shore. Spectacular cliffs rise from the shore around the Musandam Peninsula near the Strait of Hormuz. The Tigris, Euphrates, and Kārūn rivers deposit large amounts of silt as they empty into the gulf in the north-west. The area is known for its high temperatures, uncomfortable humidity, and low rainfall.
The kidney-shaped Persian Gulf and the surrounding areas contain about 68 percent of the world’s proven reserves of petroleum and about 34 percent of total natural gas reserves (2000 estimate), and new reserves are still being found, both on land and offshore. Large amounts of oil are refined in the area, and oil tankers carry oil from marine terminals to all parts of the world. Major offshore oil fields include Khafji, Hout, and Safaniyah, the largest oil field in the world (Saudi Arabia); main offshore gas fields belong to Qatar (North Dome Field), Saudi Arabia (Dorra), and Iran (South Pars). In 2000 the Persian Gulf states produced almost 28 percent of the world’s oil. The principal ports on the Persian Gulf include Kuwait, in Kuwait; Basra, in Iraq; Ad Dammām and Al Jubayl, in Saudi Arabia; Ābādān and Būshehr, in Iran; and Mīnā’ Salmān, near Manama, in Bahrain. Major oil spills in 1983, during the Iran-Iraq war, and in 1991, during the Gulf War, have adversely affected the gulf environment, as has oil pollution from routine tanker operations.