In the 18th century, monks from Stavelot’s abbey created an oxbow lake on the Amblève by digging a short-cut river channel at the tiny hamlet of Coo (pronounced 'Koe'). Cascading 15m this forms Belgium’s tallest 'waterfall'. It's no Niagara, but cupped in a pretty woodland valley, the scene is charming at dusk once the hordes of day trippers have gone home. Meanwhile, by day, if you can stand the summer crowds, Coo makes a useful starting point for all manner of outdoors activities.