Bahrain Island is the largest island within the archipelago of Bahrain, and forms the bulk of the country's land mass while hosting the majority of its population. Around most of the Island of Bahrain is a relatively shallow inlet of the Persian Gulf known as the Gulf of Bahrain. The seabed adjacent to Bahrain is rocky and, mainly off the northern part of the island, covered by extensive coral reefs. Most of the island is low-lying and barren desert. Outcroppings of limestone form low rolling hills, stubby cliffs, and shallow ravines. The limestone is covered by various densities of saline sand, capable of supporting only the hardiest desert vegetation such as chiefly thorn trees and scrubs. A 5 km (3.1 mi) wide fertile strip of land exists along the northern coast on which date, almond, fig, and pomegranate trees grow. The interior contains an escarpment that rises to 134 m (440 ft), the highest point on the island, to form the Mountain of Smoke, named as such due to the mists that often wreathe the summit. Most of the country's oil wells are situated in the vicinity of the mountain.
Manama, the capital of the kingdom of Bahrain, is located on the northeastern tip of the Island of Bahrain. The main port, Mina Salman, is also located on the island. as are the major petroleum refining facilities and commercial centers. Causeways and bridges connect Bahrain to adjacent islands and the mainland of Saudi Arabia. The oldest causeway, originally constructed in 1929, links Bahrain to Al Muharraq, the second largest island. Although the island is only six kilometers long, the country's second largest city, Al Muharraq, and the international airport are located there. A causeway also connects Al Muharraq to the tiny island of Jazirat al Azl, the site of a major ship-repair and dry-dock center. South of Jazirat al Azl, the island of Sitrah, site of the oil export terminal, is linked to Bahrain by a bridge that spans the narrow channel separating the two