Lake districts occupy a strip of width from 40 do 90 km, covering a total of over 20% country area. The Lower Vistula Valley divides this belt into the Pomeranian Lake District and the Masurian Lake District. The landscape of the lake districts is exceptionally varied thanks to the wealth of three main landscape elements: hills, lakes, forests. The lake districts are characterized by a concentration of lines of frontal moraines of lakes. Within the embankment running parallel to the coast line, the moraines reach three significant heights: the highest peak in the Kashubian Lake District - Wieżyca (329 m) and in the Masurian Lake District - Góra Dylewska (312 m) with the memorable Grunwald and the Szeskie Hills at its foot (309 m) in the northeastern part. The sculpture of the lake districts is the result of the activity of the Scandinavian ice sheet, which in the Ice Age overlapped the territory of Poland. Subsequent processes have managed to effect changes in configuration to a very limited extent. There are numerous lakes in the lake district. The largest of them are concentrated in the eastern part of the Masurian Lake District, like for example. Sniardwy lake (113,8 km2) i Mamry (104,4 km2).