Lagoon of el Campillo Nature · Rivas-Vaciamadrid, Área Metropolitana, Madrid A body of water of some 35 hectares and about four kilometres in diameter, located in the Sureste regional park, in Rivas-Vaciamadrid (Madrid), formed from gravel pits worked in the Jarama river valley during the 1960s and 1970s as excavation went below the water table; after the activity ceased and the surroundings were restored, it is today the park's second-largest lagoon by area, after that of El Porcal. Beside it ran the route of the old Tajuña railway, opened in 1886 and closed in 1997, along which the Tren de Arganda now runs, a tourist service with historic rolling stock between La Poveda station and a siding beside the lagoon, where there is also a nature interpretation centre. Photo: Crimeanmedal (CC BY-SA 3.0 es) What to see and do in Rivas-Vaciamadrid