The Kückelheim Tunnel, a 689-metre-long structure, is a characteristic element of the SauerlandRadring. This cycle path stretches over 84 kilometers on former railroad lines through the heart of the Sauerland and connects villages such as Finnentrop, Eslohe, Schmallenberg and Lennestadt. Inside the tunnel, damp quarry stone walls and subdued lighting create a special atmosphere. In the cooler months, the structure serves as an important winter roost for various bat species, including the bearded bat, the greater mouse-eared bat, the water bat and the brown long-eared bat. These zoological inhabitants also inspired the pictogram of the cycle path, which depicts a cyclist in front of the silhouette of a bat. During the conservation phase, the tunnel is temporarily closed to visitors.