It follows a northerly circuitous course in the hill tracts[1] and then enters Bangladesh near Remaikri, Thanchi Upazila, Bandarban District, from the east.

[2] The Sangu River drainage basin has a total area of 3,843 square kilometres (1,484 sq mi).

[1] In 1876, William Wilson Hunter described the river as shallow, but navigable year round by large cargo boats for a distance of 48 kilometres (30 mi).

[4] A century later the Bangladesh District Gazetteer for the area said the river is not navigable late in the dry season.

[2] The offshore Sangu Gas Field is located in the Bay of Bengal about 50 kilometres (31 mi) southwest of Chittagong at a depth of 10 metres (33 ft).