Guarapiranga Reservoir, Water reservoir in São Paulo, Brazil

Guarapiranga is a reservoir in the southern part of São Paulo that covers roughly 26.6 square kilometers and stretches almost 20 kilometers in length. Its shoreline alternates between forested hills, residential areas, and open sections with marinas.

Construction began in 1906 under the São Paulo Tramway, Light and Power Company, initially named Represa de Santo Amaro, and the dam was inaugurated in 1908 to supply the Parnaíba hydroelectric plant. In 1928 the reservoir switched to supplying drinking water for the growing metropolis. That same year Italian aviators Francesco de Pinedo, Carlo del Prete and Vitale Zacchetti landed here after one of the first South Atlantic crossings.

The name comes from the Old Tupi gûarapiranga, "red guarás": the guará bird is born black and turns red as it grows. The reservoir's 28 km of shores host yacht clubs such as São Paulo Yacht Club, founded near the dam in 1912, and Yacht Club Santo Amaro, which trained several sailing champions.

Access to the water happens through public parks and private clubs at different points along the shore. Some areas allow walks along the waterline while other sections remain visible only from outside.

Several small islands lie scattered across the water and offer habitats for birds and other regional wildlife. These islands also help prevent flooding in the surrounding area.