Steung Saen River (ស្ទឹងសែន), sometimes spelt Steung Sen, is a river in Cambodia. It is a major tributary of the Tonlé Sap River. The Stung Sen River Basin is the largest among the 11 main tributaries around Tonlé Sap with a catchment surface of 16344 km2. The basin receives about 1500 mm of rain per year. The river passes through Preah Vihear Province and Kampong Thom Province. The northern extent of the river basin corresponds to the border with Thailand as in 1904, Siam and the French colonial authorities ruling Cambodia formed a joint commission to demarcate their mutual border to largely follow the watershed line of the Dângrêk mountain range.

Etymology

Steung Saen (ស្ទឹងសែន) means "river of soldiers" in Khmer. Steung (ស្ទឹង) means river in Khmer, while Saen (សែន) is derived from the Sanskrit word Sena (सेना), meaning "soldier".