The characteristic feature of the region are hills divided by deep lake valleys, shaped by the last glaciation in Poland. The highest hills reach up to over 300 m (Szeska Gora 309 m asl, Tatarska Gora 301 m asl).

The unique natural values of the region are protected by law in a number of nature reserves and landscape parks: Mazury Landscape Park and Suwalki Landscape Park, as well as Wigry National Park.

Pojezierza Mazurskie (Masuria Lakeland District) spreads over the area of 13,000 km2. The biggest complex of lakes, Great Masurian Lakes, is located here. The lakes are connected with streams, rivers and canals and make up a complex hydrological system. Two biggest lakes in Poland – Sniardwy and Mamry are located here. The region is covered by dense forest. The biggest forest complexes are located in the southern part of the Masurian Lakeland: Puszcza Piska (Piska Forest), the second largest woodland territory in Europe and Puszcza Napiwodzko-Ramucka (Napiwodzko-Ramucka Forest).

Pojezierze Litewskie, within the territory of Poland has the area of 3,500 km2. The landscape of Pojezierze Litewskie is slightly different from that of Pojezierze Mazurskie. The climate here is continental, and Pojezierze Litewskie is considered to be the coldest part of Poland. The biggest forest complexes of the area are: Romincka Forest (Puszcza Romincka) and Augustowska Forest (Puszcza Augustowska).