The Jaldhaka River is a trans-boundary river, with a length of 192 Kilo metres. The river originates in southeastern Sikkim in the eastern Himalayas and flows through the Jalpaiguri and Cooch Behar districts of West Bengal, India. At that point the river enters Bangladesh crossing the Lalmonirhat District and then joins with the Dharla River until the Dharla debouches into the Brahmaputra River near the Kurigram District. Due to the river`s travel over many international borders, only a small length of the river flows within Bangladesh.

The Jaldhaka River is formed by the combination of three streams at Bindu, the descending point of the Jaldhaka Police Station at Darjiling district in West Bengal. The three streams are known as Dudh Pokhri, Bindu Khola, and Jaldhaka, which takes birth in the small glacial lake the Kupukh Pokhri. The merged streams meet at Bindu to form the Jaldhaka River thus forming a riverine periphery with India and Bhutan in the left bank. The main tributaries that join the river in its right bank are the Murti, Naksal Khola and the Sutunga in the last course.

The Diana is the main tributary on the right bank. The river flows across the three North Bengal districts of Jalpaiguri, Darjeeling, and Koch Bihar. The entire watershed is the most fertile agricultural zone along with the Teesta Basin. The Upper course is famous for crops like ginger, medicinal herbs and fruits like oranges and pomegranate. The middle course comprising of Jalpaiguri district is entirely tea and corn dominated and the lower course is filled with the harvesting of rice, jute and tobacco. The inter river formed lands are cultivated with crops like bamboo and mat sticks. In the lower basin the inter river lands are cultured with banana. The river enters Bangladesh at Ghoksadanga district and meets the Brahmaputra or the Jamuna River, as it is known there.