A diversion out of Ponterwyd enables you to climb Pumlumon. At 752m., Pumlumon is mid-Wales’s highest mountain. It is really not one mountain but five – pump means ‘five’ in Welsh. The summit is Pen Pumlumon Fawr, ‘the top of Big Pumlumon’.
Pumlumon is one of the Five Holy Mountains of Wales. It is also the source of five rivers. The Teifi flows south-west to Cardigan, the Rheidiol and the Ystwyth tumble rapidly down to the coast at Aberystwyth, and the Wye and the Severn make their long way east and south to meet again at Chepstow.
To reach Pumlumon, leave Ponterwyd by the minor road to the east of the Afon Rheidol. Ignore the green road from Hirnant marked on the map and take the stony forest road from SN 75828 84791 up and into the forest. The old green road is marked on the map running right at the forest entrance and turning left through the trees, but it is difficult to find on the ground.
The forest road becomes a rough muddy track and joins the line of the green road.
At SN 78632 84095, leave the forest and turn left along the forest edge. As you climb, magnificent views open out across the Rheidol and Wye valleys and over the Dyfi to the mountains of the north.
You can keep to the forest fence or cut acros the angle to join the track which goes up the right hand side of the fence along the ridge. From the northern cairn the route goes slightly west of north down the ridge. There is a track above the crags which cuts down to the dam below Llyn Llygad Rheidol, the ‘Eye of the Rheidol’. The easiest way across the stream is to walk through the half inch or so of water which flows over the dam. A faint track on the far side of the bridge leads down to the footbridge over the Afon Hengwm.
More about the area on the Pentir Pumlumon site.