I did a “round trip”:https://www.silvertraveladvisor.com/review/attraction/200650 on the Welsh highland Railway in October 2019. This is one of a series of short reviews with pictures of different parts of the line.
From Nantmor, the line enters mixed deciduous woodland before entering the Aberglaslyn Gorge. This is one of the most dramatic parts of the run. The River Glaslyn has cut a deep and narrow gorge through the mountains which is shared by the track of the Welsh Highland Railway and the A498.
The track runs along the hillside and through three tunnels before emerging into the top of the gorge. Before the railway was rebuilt, this was a popular public footpath. Armed with torches, we had walked through the tunnels many times. The first tunnel is the longest at 300 yards and there is a slight bend and in the centre making it impossible to see daylight.
Now there is a properly made footpath through the gorge below the railway line. It must surely rank as one of the best “walks”:https://www.nationaltrust.org.uk/craflwyn-and-beddgelert/trails/cwm-bychan-and-aberglaslyn-pass-walk in the area.
Approaching Beddgelert, the gorge widens into a flat valley bottom. The remains of old tramways can be seen heading to Beddgelert including two stone pillars from a “bridge”:https://en.wikipedia.org/wiki/Portmadoc,_Beddgelert_and_South_Snowdon_Railway#/media/File:PBSSR_abutments_at_Beddgelert.jpg that was never built.