Walk, drive or cycle the 4 kilometres along the road to the gate to the Marchlyn Mawr reservoir, then continue along the private road until you see a stile with a sigh marked “footpath to Carnedd y Filiast”. The route on the map takes you over the summit and over the summits of Mynydd Perfedd and Elidir Fawr before returning you to the reservoir road. Hiking boots are recommended, there are some tricky granite slabs at odd angles at some of the peaks.
Total distance on foot from Graianfryn is 17.5 km, about 6.5 hours.
If you have a car, about 20 minutes driving and five hours walking.