Welsh Three Peaks Challenge Route Postcodes for the most common parking at each mountain are: Snowdon - LL55 4NY for Pen-y-Pass (Pyg Track route), or LL55 4TY for Llanberis. Cadair Idris - LL36 9AJ, Dôl Idris Car Park. Pen y Fan - LD3 8NL, parking opposite the Storey Arms. Driving Route The Welsh Three Peaks driving route, north to south, is as follows: Snowdon to Cadair Idris Taking approximately an hour and a half. A4086 south from Llanberis through Pen y Pass Left onto A498 through Beddgelert to Aberglaslyn, left over bridge onto A4085 At Garreg, left onto B4410 At Maentwrog, left onto A487 Carry on to A470 past Trawsfynydd down to Dolgellau After Dolgellau, right onto the A487 by the Cross Foxes Inn Left just after the Minffordd Hotel to the Dôl Idris car park Cadair Idris to Pen y Fan Taking approximately two hours twenty minutes. A487 south to Machynlleth Left at the town clock and right in the middle of the town onto Forge Road Right at the T-junction onto B4518 to Llanidloes First exit at roundabout in Llanidloes and then right at second, onto A470 Through Rhayader, Builth Wells, Brecon, remain on A470 At the Storey Arms, parking is either immediately opposite or 200 metres further on the left.