The port city ofSurabaya is built along the river. The old Surabaya harbour, built centuries ago, is located near the river mouth. At one point in time, this was an entry port to the Kingdom of Majapahit, and it is also here that the founder of Majapahit empire fought off a Mongol invasion in 1293. During the times of the Dutch East Indies, this river was heavily utilized as a goods transport route. Large trade ships unload commodity goods at the strait of Madura, where smaller ships take over and distribute the trade goods inland. The Kali Mas harbour was built to facilitate such trade. The areas along Kali Mas was split into two, which are called Westerkade Kalimas dan Oosterkade Kalimas, and in the local dialect are known as Kulon Kali and Wetan Kali respectively. The areas east of the river were developed for trade and commercial activities. These include Kembang Jepun, Cantikan, Kapasan. The west side includes Gresik road, Kalisosok, and the area around west Tanjung Perak. With the development of land based transport river transport along the Kali Mas has largely been diminished. Due to its long history serving as a major transport route, many historical buildings can be found along the river bank. These include the Kali Mas harbour, old settlement and trading houses along the river banks, as well as the residence of the governor. There is also a collection of old bridges, including the famous historical landmark Jembatan Merah, as well as a drawbridge.
Current use
Following an extensive program to clean up the river and relocate squatters along parts of the river banks, the Surabaya city administration is planning to develop the area for recreation as well as cultural functions. With a budget of 9 Billion Rupiah, 9 areas along the river banks are planned to be revitalized starting from 2008. Water quality improvement programs are also underway, with some assistance from the city of Kitakyushu, Japan. Periodically, live fishes are released into the river to improve on its ecosystem biodiversity. Current uses of the river include river cruise, boat racing, and boat carnival. Some trade activity still exist at the Kalimas Harbour.
