someone told me there was a nice waterfall at Coo may try to find that while we're there.
That's worth a visit and very easy to find, next to the N633. Coming out of Stavelot, just follow the signs to Trois Ponts and then La Gleize, you'll pass by the waterfall (or look out for signs "Plopsa Coo", an amusement park next to the waterfall).