tl;dr: Germany is completing a decades-long, €13.8 billion project to convert former East German lignite mines in Lusatia into Europe's largest artificial lake landscape, totaling 144 km² — nearly the size of Lake Como. The final piece, Lake Sedlitz, opens for swimming and boating on April 24, and by June 2026, five lakes will be connected by navigable canals into a contiguous 5,000-hectare water area. The lakes also serve as drought reservoirs and are driving a tourism boom, with the region pitched as a model for other coal regions facing structural transition.