The Jaldhaka River is a trans-boundary river, with a length of 192 metres, that 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 through 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 wondering over several international borders, only a small length of the river lies within Bangladesh.
The Jaldhaka River is formed by the conjunction of three streams at Bindu, the end point of the Jaldhaka Police Station at Darjiling district in West Bengal. The three streams are known as Bindu Khola, Dudh Pokhri and Jaldhaka which originates from the locally named small glacial lake the Kupukh Pokhri. The combined streams meet at Bindu to form the Jaldhaka river thus forming a riverine boundary 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 right bank tributary. The river flows through the three North Bengal districts of Darjiling, Jalpaiguri 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 dominated by 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 cultivated with banana.
The river enters Bangladesh at Ghoksadanga district to meet the Brahmaputra or the Jamuna as it is known there.