All walks › Brecon & the Usk Valley
Brecon & the Usk ValleyLlyn Cwm Llwch
Walk to a glacial lake sitting in a deep hollow under the north face of Corn Du, without the commitment of going to the summit.
- Distance
- 4.3 mi / 7 km
- Time
- 2 hr 30
- Ascent
- 300 m
- Difficulty
- Demanding
- Shape
- There and back
Where it is
The circle shows the general area, not the exact start. Use the directions link below to get to the car park itself. Contours and paths shown are OpenTopoMap, drawn from OpenStreetMap data.
The route
Follow the track up the valley from the car park, climbing gradually into the cwm until the lake appears beneath the crags. Return the same way, or continue up to the ridge if you have the legs and the weather.
Worth knowing
- A good half-day objective that gives you real mountain scenery without four hundred and eighty metres of climb.
- The obelisk on the slope above commemorates a child who died on the mountain in 1900.
- The car park is tiny and the lane in is narrow. Go early.
What you’ll see
The tarn, the north face of Corn Du, ring ouzel and wheatear in season.
Background
The lake sits behind a moraine left by the glacier that carved the cwm. Legend gave it a hidden island and a doorway to Annwn, open one day a year until a visitor stole a flower and it closed for good.