Fen area
The fens of several hectares are located in a 70-hectare wooded area in a wide bowl-shaped valley of the Lollebeek. The maximum depth is 50 cm but often much less. The peatland was created by the stagnation of ground and rainwater runoff. The peat was largely excavated in the early 20th century by peat diggers, creating open pools. Today, the area consists mainly of wetland forest and, to a small extent, grassland.
Unusual flora and fauna
A walk through the jungle-like nature in the Castenrayse Vennen is a real experience. The area is also home to a number of special plants such as the Snake Root, Water Strawberry, Water Violet and King's fern.