Surabaya is Indonesia's second-largest city with a population of over 3.1 million (5.6 million in the metropolitan area), and the capital of the province of East Java. It is located on the northern shore of eastern Java at the mouth of the Mas River and along the edge of the Madura Strait.

To some Indonesians, it is known as "the city of heroes" due to the importance of the Battle of Surabaya in galvanizing Indonesian and international support for Indonesian independence during the Indonesian National Revolution. Surabaya is also known as the birthplace of Indonesia first president, Sukarno.