A woodland waterfall near Garreg Ddu reservoir in the Elan Valley. It's only a 10 minute walk from the car park by Nantgwyllt Church. Follow the track which runs along the side of the reservoir. When you get to a sharp corner where the reservoir ends, there's a foopath by the stream straight ahead, and the waterfall is a couple of hundred yards further. The path continues through the wood and onto moorland.