The Rio de Piracicaba is a 115-kilometer river in the interior of São Paulo state, formed at the confluence of the Atibaia and Jaguari rivers in the municipality of Americana. From there it flows generally westward, passing through the city of Piracicaba — where it receives its principal tributary, the Corumbataí River — before emptying into the Tietê River within the reservoir created by the Barra Bonita Dam, between the municipalities of Santa Maria da Serra and Barra Bonita. The river's basin covers approximately 12,531 km², spanning the southeastern portion of São Paulo state and the extreme southern edge of Minas Gerais.

The river's name derives from a Tupi expression meaning "place where the fish stops," a reference to its pronounced meanders. Those meanders are a defining characteristic of the lower reach: the winding course downstream of the city of Piracicaba is suitable for navigation by small boats, making that stretch the most relevant section for paddlers. The city of Piracicaba itself sits roughly 150 km northwest of the state capital, São Paulo, and has historical ties to the river dating to its founding in 1767.

The post-Piracicaba meanders offer the best paddling opportunities, though conditions vary with the season and water levels. Paddlers should be aware of the transition near the Barra Bonita Dam, where the river flows into the reservoir backwater and the character of the paddling changes significantly. Local knowledge is essential for planning a trip, particularly regarding current water conditions and any hazards specific to your intended route.