It is a natural watercourse that rises at the foot of Cerro Tronador.
The upper Manso River goes for approximately 17 kilometres. its waters are turbid, whitish or milky colour. It ends when it flows into Lake Mascardi.
The middle Manso River runs through a deep and rugged valley, oriented from north to south, between rapids and waterfalls, the most spectacular and famous is Cascada los Alerces.
Lower Manso River, about 50 km long in Argentinean territory, is again a gentle course, with few rapids.