Czarna Hancza
The Czarna Hańcza, Čornaja Hanča (Belarusian: Чорная Ганча, Lithuanian: Juodoji Ančia) is the largest river of the Suwałki Region of north-eastern Poland and the Sapockin region of north-western Belarus. It is known for having large postglacial boulders. Originating near Lake Hańcza (the deepest lake in Poland with the maximum depth of 108.5 m) and flowing through lake Hańcza and Wigry Lake (the location of Poland's Wigry National Park), it is a tributary of the Neman River beyond the borders of Belarus and Lithuania.
Coordinates: 53°54′1″N 23°47′5″E / 53.90028°N 23.78472°E
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