In the Kottenforst, a Maar is not a volcano's crater, as it would be in the nearby Eifel, but a small pond or wet hollow in the forest floor, and the Pfaffenmaar, the priests' pond, is a good example. The word has been used locally for centuries for any round, water-filled depression, and these hollows give the forest a dotted pattern of reeds, alders and dark water. The reason is the heavy clay under the thin soil, which holds rainwater and keeps parts of the woods boggy for much of the year.
The result is a forest with a wetland character, and it supports a lot of life. Amphibians breed in the ponds, with newts, frogs and toads in spring, dragonflies hover over the water in summer, and the damp ground suits alder and willow. Woodpeckers hammer in the oaks, and at dusk, you may see a roe deer at the edge of a clearing. The forest smells of wet leaves and moss, even on a dry day.
Underneath the woods runs the line of the Roman aqueduct that brought spring water from the Eifel to Cologne, a channel about ninety-five kilometres long, mostly buried, built in the first century. Along its route, paths and information boards mark where it can be seen, and in a few places along the Villerucken ridge, you can still see parts of the structure. It is one of the longest aqueducts of the Roman world, and its presence here, in a quiet forest, comes as a surprise.
Motorcycles cannot use the woodland tracks, so the riding is on the public roads that border the forest, which are quiet and tree-lined. Watch for cyclists, walkers and dogs, especially at weekends, and for wet leaves in autumn. Alfter and the nearby city of Bonn offer fuel, food and rooms, and the Rhine promenade is a pleasant place for a rest. Spring, when the forest is fresh, and the frogs are loud, is lovely, and winter has its own bare-branched charm. Boots help if you want to explore on foot.