The Rio Paranapanema is one of Brazil's most significant river systems, stretching approximately 930 km through the interior of southeastern Brazil before draining into the left margin of the Rio Paraná. The river originates in the state of São Paulo near the municipality of Capão Bonito, protected by the State Parks of Intervales and Carlos Botelho, and flows westward through a basin covering roughly 106,500 km² across 247 municipalities — 115 in São Paulo and 132 in Paraná. From the confluence with the Rio Itararé, the Paranapanema forms a natural border of approximately 330 km between the states of São Paulo and Paraná, making it a defining geographic and ecological feature of the region. The river supports an extraordinarily diverse fish community, with over 225 recorded species across the basin, and its cascade of reservoirs along the lower reaches adds significant variety to the fishing opportunities available to anglers.