Cwm Clydach is a nature reserve established in 1987 after the RSPB found a large number of breeding birds that were not common in the area. This nine mile circular walk, travels alongside the lower Clydach River through peaceful woodland, onto unspoilt common land with sites of archaeological interest and spectacular views towards the Brecon Beacons. The reserve is a mixed broadleaf woodland with a wide variety of bird species present including Buzzard, Red Kite, Green and Great-Spotted Woodpecker, Nuthatch, Treecreeper, Bullfinch, Dipper, Grey Wagtail, Spotted Flycatcher, Willow Warbler Blackcap, Pied Flycatcher, and Redstart, as well as a wide variety of butterflies.
Until 1962 much of Cwm Clydach was a working coal mining valley and evidence of the mines can be seen as the route follows the old tramway up the valley. From the river, the route climbs up and over the common, passing the Llechart Burial Mound, a ring cairn of 25 stones thought to be all that remains of a burial mound dating to about 1500 BC, and Gellionnen Chapel, built in 1692 and considered to be the oldest nonconformist chapel in the area.