Seliger (Russian: Селиге́р; IPA: [sʲɪlʲɪˈgʲer]) is a lake in Tver Oblast and, in the extreme northern part, Novgorod Oblast of Russia, in the northwest of the Valdai Hills, a part of the Volga basin. Absolute height: 205 m, area 212 km², average depth 5.8 m.
Seliger is a large system of lakes linked by effluents, has many small islands and is surrounded by forests, including pine woods with many berries and mushrooms. 
Seliger is situated within a picturesque landscape of forests and hills. The lake is a protected nature reserve and is sometimes known as the "European Baikal" due to the diversity of its unique flora and fauna, similar to Lake Baikal.
Ostashkov is the only town on the lake and is one of the most popular resorts in central Russia.