Well worth the 15km trek north of Konstanz, Marienschlucht is a deep ravine wedged between the villages of Bodman and Wallhausen. A wooden staircase zigzags up through the chasm, past a babbling stream and 30m-high cliffs thick with lichen and ferns. The top rewards with snapshot views of Lake Constance through the beech trees. Bear left to follow the trail along the ridge and back down to Wallhausen. There are picnic areas and a kiosk en route, as well as pebbly bays for refreshing dips in the lake.