The Nant Llech rises on the southern slopes of Carreg Cadno and flows to the village of Coelbren at which point it drops over the lip of a faulted block of the Farewell Rock, a hard sandstone. This spectacular site and section of the gorge below the falls is owned and managed by the National Trust. The waterfall is referred to in Welsh as Sgwd Henryd or as Rhaeadr Henryd.