Flowing out of the pristine Lago Riñihue — the last of the celebrated chain of eight Andean lakes in the Valdivia River Basin — the Río San Pedro is a renowned fishing destination in the Los Ríos Region of southern Chile. The river runs approximately 40 kilometers from the outlet of Lago Riñihue to its confluence with the Collileufu River, where it transitions into the Calle-Calle River, which eventually becomes the Río Valdivia and empties into Corral Bay. Fed by the outflow of a pristine Andean lake system, the Río San Pedro carries exceptionally clear water through a landscape of native southern Chilean forest, making it one of the most scenic and productive fisheries in Patagonian Chile. The river is well known not only for its fishing but also for its powerful whitewater, a combination that speaks to the river's energy, gradient, and dynamic character.