The Manzanares River flows from the Sierras de Guadarrama, passing through Madrid on its way to the Jarama River. It is the city's main river and offers a host of recreational activities from fishing and water skiing to hiking the Natural Reserve around the river's upper basin. Madrid Rio, the main riverside park, stretches six miles along the riverbanks with playgrounds, green spaces, beaches, sports courts, historic monuments and a tree-lined promenade. Also, check out Playa Madrid, a large and popular reservoir near the Zarzuela Hippodrome.