From Caernarfon to Llanwnda Station the Lôn Eifion runs alongside that of the Welsh Highland Railway.
[2] At the Llanwnda station the Lon Eifion continues south over Glanrhyd to the A487/A499 Pwheli/Porthmadog roundabout, which prior to the Penygroes bypass,[3] was the site of the old Llanwnda Rail Station[4][circular reference] on the Carnarvonshire Railway.
Once over the foot bridge the Lon Eifon cuts through woodland heading due South, passing the rear of Inigo Jones Slate Works[8] and further on to open field land with views to the West of Pontllyfni[9] and Aberdasach[10] and The Rivals[11][circular reference] until reaching another footbridge at the end of Clynogg Road and continuing down to the roundabout of A487/B4418.
It continues on a much quieter and greener route along the old railway line through trees and farm land down to Bryncir.
Walkers can take the Lôn Goed path from near Bryncir to the coast at Afon Wen.