kotamadya (municipality) and capital of East Java (Jawa Timur) (Jawa Timur) propinsi (province), Indonesia. It is situated on the northeastern coast of Java and lies along the Surabaya Strait opposite Madura Island. The canalized Mas River, which is a branch of the Brantas River, flows through the centre of the city.

Surabaya has been the chief trading centre of eastern Java since the 14th century. Occupied by Japan during World War II, the city was heavily bombed by the Allies and was damaged again during Indonesia's war for independence (1945–49). In November 1945 a fierce battle was fought in Surabaya between Indonesian nationalists and British troops who were attempting to assert Allied control, which was interpreted by the nationalists to mean a prelude to the return of the Dutch.

Surabaya's port, Tanjungperak, lies just north of the city and next to Ujung, Indonesia's main naval station. Of Indonesian cities, Surabaya is surpassed in size only by Jakarta and has remained the chief commercial centre of eastern Java. From its port is shipped the bulk of Java's chief agricultural product, sugar, as well as coffee, tobacco, teak, cassava, rubber, spices, vegetable oils, and petroleum products. The city also has a large fishing fleet. The city's industries include shipbuilding and ship-repair yards, locomotive workshops, and the manufacture of textiles, glass, chemicals, beer, cigarettes, and shoes. A suburb has a petroleum refinery. The surrounding area is a flat, rich agricultural region. Surabaya is linked with the rail and road system that connects the eastern and western coasts of Java and is thus in communication with the other chief cities of the island. It also has major shipping communications with the chief ports of the Indo-Pacific region, because it lies along the main sea route from Singapore and Jakarta to the Pacific and eastern Asia. There is an airport at Tanjungperak.

Notable sites in the city of Surabaya include a large mosque (1868); Airlangga University (1954), with faculties of law, medicine, and dental surgery; the Tenth of November Institute of Technology (1960); a naval college; and the old Dutch colonial Fort Prins Hendrik. Pop. (2005) 2,611,506.