The Rio Paraibuna is a 116-kilometer river in São Paulo state, southeastern Brazil, flowing as a tributary into the Paraíba do Sul. Its headwaters fall within the 292,000-hectare Mananciais do Rio Paraíba do Sul Environmental Protection Area, established in 1982 to protect the sources of the Paraíba do Sul river system.

The river feeds the Paraibuna Reservoir (Represa do Rio Paraibuna), located near the town of Paraibuna in the Paraíba Valley. The reservoir is a recognized destination for kayaking and boating. One noted paddling route runs from Paraibuna toward Natividade da Serra. The reservoir's geography is complex, with numerous islands and arms that can disorient paddlers; carrying a physical map rather than relying solely on GPS is strongly advised.

Access to the reservoir's launch points is primarily via dirt roads that run along its edges. These roads can be uneven and rutted, so a vehicle with reasonable ground clearance is recommended to reach many of the put-in locations. There is no entrance fee for accessing the general shoreline areas, and no set operating hours apply to the reservoir as a natural water body, though paddling during daylight hours is the practical choice for safety.

Recreational vessels must be registered with the Brazilian Navy (DPC) and carry a valid Vessel Inscription Title (TIE/TIEM) before operating on Brazilian waters.