On the N slope of the turó de la Malesa. To get there, take a path that leaves on the left of the road from Terrassa to Castellar del Vallès, shortly before crossing the bridge over the Ripoll river. This path continues level as far as the turó de la Malesa, where it ends in a small square. From here a small path leads to the Ripoll river, in front of the well-known Gorg d'en Fitó; a little before reaching the river, the chaos of blocks produced by the fractures in the rock can be seen on the left. At the intersection of two of these fractures is the Avenc de la Malesa, in a spot very hidden by the vegetation, and above it, among a pile of blocks, is that of the Avenc II de la Malesa. Approximate coordinates of low precision.