Sangu river is the main river of Bandarban district. Locally conch river, hilly river. It is the second largest river in Chittagong division after Kornafuli. Sangu is one of the few rivers originating in Bangladesh. It originated in the hills of Madak area of Thanchi upazila of Bangladesh bordering Myanmar. It flows over Bandarban district and South Chittagong and merges into the Bay of Bengal. The length of this river from its source to the Bay of Bengal is 160 km. The Sangu River is closely associated with the livelihood of the district. This river is one of the means of communication in the hilly areas of Bandarban. The river is washed away in Bandarban district and southern part of Chittagong. Most of the rivers of Bangladesh flow from north to south and merge into the Bay of Bengal. But the Sangu River formed in the southern part of Bandarban, flowed north and ended in the Bay of Bengal.