The Bartang river is a river of Central Asia, tributary to the Panj river and consequently to the Amu-Darya. In its upper reaches, it is known as the Murghab River and Aksu River; it flows in the Wakhan in Afghanistan, then in the Roshan District of the Gorno-Badakhshan province, Tajikistan.
The river rises in Chaqmaqtin Lake in the Little Pamir in the Wakhan, where it is known as the Aksu ("white water"). It then flows east and crosses into Tajikistan, then turns north to the city of Murghab passing the village of Shaimak.
Below Murghab the river is called the Murghab River (Tajik: Мурғоб / Persian: مرغاب, meaning Bird River, also spelled as Murghob, Murgob, or Murgab (from Russian: Мургаб)). A few miles below Murghab is Sarez Lake, formed by a landslide during the 1911 Sarez earthquake, which created the world's highest natural dam, Usoi Dam.
The river is joined by the Ghudara river just below Sarez Lake. From the junction the river is known as the Bartang. The Bartang traces a route down the western Pamir Mountains, flowing 132 kilometers (82 mi) before becoming a tributary to the Panj River at the border of Tajikistan and Afghanistan. Much of the river lies within the boundaries of Tajik National Park. The Bartang is fed mostly by glacier and snow melt. It is the only river to cross Gorno-Badakhshan from east to west.