The Promenade de la Hoëgne in the Belgian Ardennes consists of several trails, ranging from 8-21km, and is perfect for a family walk. Trails are clearly marked and combine wooden bridges with mossy paths, boardwalks and rocky steps. They will lead you through beautiful forest and past several waterfalls, always staying close to the Hoëgne river. While it can get busy in summer, we went late afternoon on a September weekend and had most of the way to ourselves.
If you want to park as close to the trail head as possible, at the Pont de Bellehei parking, you will have to actually drive through the river! The water is usually only a few cm deep, but if you don't want to risk it, you can park the car a bit further away alongside the road.