Theres one out the back of Llangollen just off the horseshoe pass that is very good when its not high season, its in the grounds of an old chapel/church type thing.
Theres several caravan type ones around Llangollen as well, that are well, erm 'twee' I suppose. Depends what you want- but thats where I usually go when I work in Llangollen.
If the River Dee is up go whitewater rafting (and you might see me at work raft guiding :dance:) as in high water its pretty good.
If the river is low, drive up to Corwen and go through the Carwash and theres a lane called the Baddy/Baddie (something like that) that apparently is quite severe!!!