Masuria and the Masurian Lake District are known in Polish as Kraina Tysiąca Jezior and in German as Land der Tausend Seen, meaning "land of a thousand lakes." These lakes were ground out of the land by glaciers during the Pleistocene ice age around 14,000 - 15,000 years ago, when ice covered northeastern Europe.
From that period originates the horn of a reindeer found in the vicinity of Giżycko.96 By 10,000 BC this ice started to melt.
Forests account for about 30% of the area.9798 The northern part of Masuria is covered mostly by the broadleaved forest, while the southern part is dominated by pine and mixed forestsŹródło: https://en.wikipedia.org/wiki/Masuria#Landscape
Poland's territory extends across several geographical regions, between latitudes 49° and 55° N, and longitudes 14° and 25° E. In the north-west is the Baltic seacoast, which extends from the Bay of Pomerania to the Gulf of Gdańsk.This coast is marked by several spits, coastal lakes (former bays that have been cut off from the sea), and dunes.
The largely straight coastline is indented by the Szczecin Lagoon, the Bay of Puck, and the Vistula Lagoon.The centre and parts of the north lie within the North European Plain. Rising above these lowlands is a geographical region comprising the four hilly districts of moraines and moraine-dammed lakes formed during and after the Pleistocene ice age.These lake districts are the Pomeranian Lake District, the Greater Polish Lake District, the Kashubian Lake District, and the Masurian Lake District.
The Masurian Lake District is the largest of the four and covers much of north-eastern Poland.
The lake districts form part of the Baltic Ridge, a series of moraine belts along the southern shore of the Baltic Sea.Źródło: https://en.wikipedia.org/wiki/Poland#Geography