After leaving the lagoons (Y Glyn) car park we take the footpath through Coed Doctor onto Ty Du road and then just after passing the oldest house in Llanberis take the old footpath and climb up to the top Cefn Du (1441ft)
Descending by a different route from Cefn Du we follow the track past Hafod Uchaf eventually reaching the old ruin at Brithdir.From here we climb up to Cwm Dwythwch and walk along the lake side before beginning the decent back down to the track following the bank of the river.We then we make our way down back to Llanberis eventually reaching Petes Eats for a welcome refreshment.
Note. Because the bridge at Maen Llwyd Isaf has not been repaired since the floods last November, we will have to make a slight detour which will add about a mile to the walk.