The National White Water Centre uses releases from Llyn Celyn to create reliable rapids on the Afon Tryweryn, a rare advantage in Britain where many white-water rivers depend heavily on rain. It is set up for rafting, kayaking, canyoning, coaching, and rescue training.
For non-paddlers, rafting is the obvious way in. Book ahead and expect to get properly soaked; this is not a lazy river float.
It calls itself the UK's original white-water rafting company, with around forty years on the river. The two-hour Ultimate Rafting trip takes riders from age twelve; canyoning is also offered.