The Manzanares is a river in the centre of the Iberian Peninsula, which flows from the Sierra de Guadarrama, passes through Madrid, and eventually empties into the Jarama river, which in turn is a right-bank tributary to the Tagus.
In its urban section, the Manzanares River was modified to create a section of water several meters deep, in some parts navigable by canoes. This project of channeling and damming has been partially reversed in a re-naturalization project.