I'm a little unsure whether to bother posting this, but having had a quick nose around the internet I've been unable to find anything on it (probably down to me using the wrong search terms). Not found other photographs either. No indication of tunnel old or current maps (scales 1:2,500 - 1:50,000). The entrance to the tunnel is very visible from the other side of the lake.
Between Nant Peris and Llanberis in North Wales on south western side of Llyn Peris between the lake and the road (A4096), Tunnel perhaps 30m deep, lined with spray concrete, inside the back of the tunnel is blocked with reinforced concrete coming out of which are two large c.2ft diameter steel pipes with valves on the ends. The valves are wrapped in grease and fabric. The pipes sound empty. The direction the tunnel goes in probably puts the back of the tunnel somewhere under the road. There is a flat area outside the entrance to the tunnel and then it is much steeper down to the lake edge.
The are remains of old copper mines in the mountainside behind.
Uncertain whether this is related to when Dinorwig Power Station was constructed on the other side of the lake or might be earlier.
Between Nant Peris and Llanberis in North Wales on south western side of Llyn Peris between the lake and the road (A4096), Tunnel perhaps 30m deep, lined with spray concrete, inside the back of the tunnel is blocked with reinforced concrete coming out of which are two large c.2ft diameter steel pipes with valves on the ends. The valves are wrapped in grease and fabric. The pipes sound empty. The direction the tunnel goes in probably puts the back of the tunnel somewhere under the road. There is a flat area outside the entrance to the tunnel and then it is much steeper down to the lake edge.
The are remains of old copper mines in the mountainside behind.
Uncertain whether this is related to when Dinorwig Power Station was constructed on the other side of the lake or might be earlier.