The Bassac River (commonly called Tonle Bassac ទន្លេបាសាក់) is a distributary of the Tonlé Sap and Mekong River. The river starts in Phnom Penh, Cambodia, and flows southerly, crossing the border into Vietnam near Châu Đốc.
In Vietnam it is known as the Hậu River (Sông Hậu or Hậu Giang in Vietnamese).
The Bassac River is an important transportation corridor between Cambodia and Vietnam, with barges and other crafts plying the waters. A city of the same name was once the west-bank capital of the kingdom of Champasak. USS Satyr (ARL-23), a recommissioned repair ship originally built for the United States Navy during World War II, served on the Bassac River during the Second Indochina War.
- Murdoch, John B. (1974). "The 1901-1902 Holy Man's Rebellion" (PDF). Journal of the Siam Society. Siam Heritage Trust. JSS Vol.62.1 (digital): images 4–5, map image 13. Retrieved April 2, 2013.
Bassac was an important economic center, for it was the outlet for the trade from the east bank of the Mekong, including the Bolovens Plateau, Sara vane, Attopeu, and Kontum Plateau regions. From Bassac, trade in cardamon, rubber, wax, resin, skins, horns, and slaves, was conducted with Ubon, Khorat, and Bangkok.
- "The ARL-23 in Vietnam Operations Map". The ARL-23 in Vietnam. usssatyr.com. September 24, 2013. Archived from the original on September 14, 2013. Retrieved October 27, 2013.