From Crickhowell we head through Llangattock and then follow the route of a former tramroad before ascending a rough, narrow path alongside the Nant Onneu stream below the Llangattock Escarpment. The path then levels out as we continue along the valley floor to the Craig y Ciliau Nature reserve and the Waun Ddu raised bog. This wild and lovely area is home to many rare plants and trees. The route then crosses the road to descend via fields, canal and woodland back to the start point.
There are a number of stiles on the walk and a steep, narrow path on the way up.