The Rio Cachapoal flows through the O'Higgins Region of Chile, draining a basin of approximately 6,370 square kilometers before emptying into Rapel Lake. The river is 250 km long and carries an average discharge of 92.3 cubic meters per second. The lower section, which is the primary whitewater run, covers 8.5 km at class 3+/4- difficulty with an average gradient of 14 meters per kilometer (75 feet per mile).

For the lower run, the put-in is located at 880 meters elevation, approximately 3 km below Central Sauzal, reached by driving east from Rancagua 22 km on the paved Carretera el Cobre to Coya, then continuing 12 km upstream on the north side of the river. The take-out is a few kilometers below the Pangal-Cachapoal confluence at Central Sauzal, elevation 660 meters, an ENDESA hydroelectric facility in Coya; an obscure road in the center of town provides dam access. Paddlers should not put in at Central Pangal due to construction debris and a lethal low-head concrete bridge located 3 km downstream.

The run is navigable in spring, summer, and fall, with a minimum recommended flow of 1,500 CFS. None of the rapids are particularly severe, and all can be scouted from eddies without leaving the boat. The most significant hazard is a collapsed bridge on river left approximately 1 km upstream from the take-out. The river's character is notably affected by multiple dams, diversions, and mining activity in the valley, which diminishes the overall experience relative to other Chilean rivers. A collapsed bridge and industrial infrastructure are recurring features of the corridor.

At the lower end of the river near Pichidegua, where the Cachapoal meets the Tinguiririca and Rapel Lake begins to form, guided recreational kayak and SUP tours operate out of the Sector San José de Marchihue area, covering approximately 5 km of flatwater through wetland habitat. These tours are offered at a recreational difficulty level and include equipment, certified guides, and basic facilities such as parking, restrooms, and a picnic area.

The Cachapoal valley holds historical significance as the southern boundary of the Inca empire, which was unable to expand further south due to Mapuche resistance.