Masurian Lake District

The Masurian Lake District or Masurian Lake Land is a lake district in northeastern Poland within the geographical region of Masuria, in the past inhabited by Masurians who spoke the Masurian dialects. It contains more than 2,000 lakes. The district had been elected as one of the 28 finalists of the New 7 Wonders of Nature.The Lakeland extends roughly 290 km eastwards from the lower Vistula to the Poland–Russia border, and occupies an area of roughly 52,000 square kilometres.

Source: Wikipedia