The park can be broadly divided into three areas: the Northern Basin (Basen Północny), the smallest and least-visited area of the park; the Middle Basin (Basen Środkowy), stretching along the river's broad middle course and featuring a combination of wet forests and boglands; and the equally extensive Southern Basin (Basen Południowy), where most of the terrain is taken up by marshes and peat bogs. The showpiece is the Red Marsh (Czerwone Bagno) in the Middle Basin.