Two main companies, BrandSport and Ardenne Aventures, both offer a smorgasbord of outdoor activities including rope-walk adventures, mountain biking and kayaking. See their websites for ideas. Bike Zone repairs and rents quality mountain bikes.
The tourist office sells maps detailing cycling and hiking routes.
The winding Ourthe River passes through steep, wooded valleys with lovely meadows, making for appealing kayaking, or rafting when water levels are high enough (far from certain in summer). BrandSport kayakers start from Evets Parking in La Roche and have a ride back afterwards from Jupille (€15, around two hours) or Hampteau (€20, four hours). Ardenne Aventures offers hourly shuttles upriver to to Maboge or Nisramont, from where you paddle back (€16, 90 minutes or €25, five hours) to arrive at their Oasis Jetty cafe. This spot has lots of other splashy summer fun including pedalo rides, zorb balls and jumping from a platform onto 'the Blob' to catapult a friend into the river.