Llyn Llydaw

Open water, steep slopes rising on either side, and the remains of the Britannia Copper Mine scattered along the shore and hillside. The path continues uphill from here to Glaslyn, the smaller lake tucked higher in the cwm, and the Pyg Track overlooks Llyn Llydaw from above if you're on that route instead.

There is a reservoir sharing the same name, and some maps may point to the nearby reservoir rather than the lake. The natural lake is the one on the Miners' Track, at roughly 53.0689, -4.0490, between Llyn Teyrn and Glaslyn.

The full route from Pen y Pass to the summit is officially rated hard and strenuous, about 13 km return, around 6 hours, with 723 m of ascent, and it calls for good fitness and navigation skills. There's loose rock and scree higher up beyond the lake. Even the lower section is tiring, and the terrain is exposed open mountain with no shade.

The causeway was built in 1853, which avoided the need to use boats on the lake. On the shore stood a crushing mill, powered by water piped from Glaslyn through an overhead pipe onto a Pelton wheel, with ore delivered by an aerial cableway. The workings closed in 1916, and what you see now are the leftovers of that industry.

The summit route is officially popular, so expect company on the path, especially in fine weather. Cloud frequently sits low and can hide the surrounding tops entirely. The walk is open mountain with no shade along this stretch, so plan your layers and sun cover accordingly, and low sun on the water is the reward for an early start.

Proper walking boots, waterproofs and a warm layer for the wind off the water, plus all your own water and food for the day. Add sun protection, a map or downloaded route with a compass, and a charged phone, and turn back at the lake or Glaslyn if the weather closes in above you.