The River Rheidol (Afon Rheidol in Welsh) is 19 miles in length with a catchment area covering 73 square miles. It rises in the headwaters of the Nant y Moch reservoir on the western edge of Plynlimon and then flows south through the village of Ponterwyd on the main Aberystwyth to Rhayader road. Continuing south-westwards through ancient Welsh Oak woodlands, the Afon Rheidol joins with the Afon Mynach.
The river descends one of the most spectacular waterfalls in Wales at Pontarfynach (Devil's Bridge). Below these waterfalls, the river passes the abandoned workings of the Cwm Rheidol lead mine. The remainder of the meandering course of the river is through an ever-widening valley before reaching the sea at Aberystwyth.
There are a number of tourist attractions in the Rheidol Valley which include the Devil's Bridge waterfalls where three bridges, each built over the previous, span the top of a most spectacular waterfall.
Between Devil's Bridge and Aberystwyth runs a narrow-gauge steam railway - the Vale of Rheidol Railway built originally to ship metal ore from the mines. Nowdays it is a popular tourist route into the top end of the Rheidol Valley. The Valley is also home to the Cwm Rhiedol Hydro-electric scheme which has an excellant Visitor Centre with an exhibition and cafe.
The most popular activities in the Rheidol Valley include fishing, cycling and walking.