The Rio Manso is a substantial river in Mato Grosso, western Brazil, running approximately 850 kilometers before joining the Cuiabá River as a tributary. The river is impounded by the Manso Dam near Rosário Oeste, which creates a reservoir of 427 square kilometers powering a 92 MW hydroelectric facility. The surrounding landscape is characterized by rolling savanna and a large elevated plateau, typical of the Cerrado biome of central Brazil.

The river is located roughly 75 miles outside of Cuiabá, the state capital, making it reasonably accessible for those based in the city. The waters are crystal clear, with large schools of fish visible moving through the current — a reflection of the river's relatively preserved condition. Some stretches are rocky, and certain sections can run rough, so paddlers should exercise caution and consider engaging a knowledgeable local guide familiar with the river's character.

Mato Grosso experiences two distinct seasons. The dry season runs roughly from May through September, bringing hot, sunny days that can reach around 100°F (38°C) with cooler nights dropping into the 60s°F. The wet season spans approximately October through April, with significantly higher rainfall, elevated humidity, and somewhat cooler daytime temperatures due to cloud cover. The fishing season, which runs February through September with May and September considered peak months, offers a useful proxy for when river conditions are generally favorable for water-based activity.

Pousada Rio Manso, situated directly on the riverbank, provides boat access to the water and employs experienced local pilots and guides. The state of Mato Grosso has maintained protections for the river's fishery for over a decade, which has contributed to the overall health and conservation of the waterway.