Preserve is situated in the valley of Narew river, about 1 km above village Pniewo, in Łomża community. It occupies 120,07 hectares of land. Preserve constitutes the fragment of greatest complex of forests about the natural character. About the natural value of the preserve decides also the naturalness of vegetation patches situated in the valley of the large river. You can find here also a former II WW guerrilla base and natural monuments.