The Blausteinsee Leisure and Recreation Area is an artificial lake north of the Eschweiler municipality in the Aachen district of North Rhine-Westphalia, Germany. Its area is around 100 hectares and depth is 46m. It was created during the regeneration of the Zukunft opencast coal mine in the Rhineland coalfield, made by flooding the pit left by the mine with water. Today, the lake is a holiday area for the surrounding towns. The surface of the lake is 129 metres above sea level and its volume is around 25 million cubic metres. The filling of the lake began in 1994.