[7][8][9] It merges with the Barito River in Banjarmasin, flowing from the source in Martapura, Banjar Regency, South Kalimantan.

[12] The watershed area (Indonesian: daerah aliran sungai) of Martapura is 453.88 square kilometers (175.24 sq mi), with the main river length of 36,566 meters (119,967 feet), and with all tributaries has a total length of 375.91 kilometers (233.58 mi), giving a river density level of 0.828 km/km2 (1.333 mi/sq mi).

[13] The elevation difference between the upstream and downstream is 8.00 meters (26.25 ft), yielding a river gradient of 0.022%.

The warmest month is October, when the average temperature is around 28 °C (82 °F), and the coldest is July, at 24 °C (75 °F).

Media related to Martapura River at Wikimedia Commons