A complete guide to the Llyn Cwm Llwch circular walk in the Brecon Beacons National Park.
Llyn Cwm Llwch is a picturesque glacial lake that lies at the foot of Pen y Fan in the Central Brecon Beacons.
The lake is a feature on one of the hiking routes to summit the highest peak in South Wales. This is the Llyn Cwm Llwch circular, an exciting and moderately challenging trail named after the lake.
In this guide, I’ll explain the Llyn Cwm Llwch circular walk. Read on to find out about the hike including the distance, duration, difficulty and where to park your car.
Llyn Cwm Llwch circular walk route
- Distance: 11 km
- Duration: 4-6 h
- Elevation gain: 675 m
- Summits: Pen y Fan (886 m), Corn Du (872 m)
- Difficulty: medium
- Parking: Cwm Gwdi car park
The Llyn Cwm Llwch circular walk starts and finishes at the Cwm Gwdi car park. You can tackle it clockwise or anti-clockwise, but I recommend going clockwise. This way you summit Pen y Fan sooner.
Overall, the hike is challenging but not difficult. However, there are a couple of small sections where the trail is hard, including a few metres of grade 1 scrambling.
Cwm Gwdi car park
Find a spot in the Cwm Gwdi car park and pay the fare. There is a pay and display machine that accepts in-app payment.
Head uphill and leave the car park by passing through the wooden gate. After this there is a clearly-marked muddy trail to follow. The terrain opens up as you enter a sloping field.
The path forks in the field and you’ll want to head to the left uphill. Now you join the Cefn Cwm Llwch ridge where the trail becomes a lot steeper and uneven underfoot.
Cefn Cwm Llwch ridge
The ridge encompasses the bulk of the Llyn Cwm Llwch circular walk covering roughly 4 km. After the initial climb, the trail becomes less steep and generally easy to walk once you’ve reached the top.
On a clear day you’ll get your first mountain views while walking along the top of the ridge. You can also look in the opposite direction to see spectacular views over the open country towards Brecon.
Cefn Cwm Llwch ridge takes you all the way to the summit of Pen y Fan. As you approach the summit the trail once again becomes steep. A few metres down from the summit you’ll have to scramble over large rocks. Take care at this point as the underfoot is mostly loose stones and rocks.
The scramble brings you up to the summit. Enjoy the mountain view from the peak of the Central Brecon Beacons.
Summit of Corn Du
The next stage of the Llyn Cwm Llwch circular walk is to head over to Corn Du from Pen y Fan. The trail is clearly marked and will lead you from summit to summit.
It’s a short walk from Pen y Fan to Corn Du with a slightly steep section as you climb from the saddle between the 2 summits.
The Tommy Jones obelisk
Leave the summit of Corn Du by taking the steep path to the west. At first, the start of this steep trail looks like a sheer drop, but as you get closer, you’ll see that it is in fact a trail.
After a few minutes the path will fork. Keep right by taking the narrow trail near to the edge of the mountain face. It’s a steep drop beyond the edge, so I wouldn’t walk too close to it.
Shortly you’ll come to Tommy Jones’ obelisk. This is a stone obelisk built in memory of a young boy named Tommy Jones whose body was found where the obelisk stands.
The story of Tommy Jones is engraved on the obelisk. Sadly, he went missing one night in 1900 and was found dead almost a month later.
Llyn Cwm Llwch
From Tommy Jones’ obelisk you can see Llyn Cwm Llwch nestled in the valley floor right in front of Corn Du’s north face. The narrow trail curves down the western approach to Corn Du, almost coming back on itself as you drop down to the lake.
The underfoot is tricky in places here and the final descent to the lake’s shore is quite steep. Once you’re down, there are large rocks at the shore which you can sit on to take in the scenery.
Farm house
Leave Llyn Cwm Llwch behind and head away from the Central Brecon Beacons following the well-marked path. The next feature on the Llyn Cwm Llwch circular walk is a farm house roughly 2 km from the lake.
Once you get to the farm house, you’ll need to hop a style to the left of the path. This brings you on to a dirt road.
Return to the car park
Follow the dirt road which eventually becomes a tarmac surface. At the crossroads head right and continue along the road until you come to a 3-way junction. At this junction you also need to head right.
Follow the road until you come to a final junction. Head right again here and the road takes you up into Cwm Gwdi car park.
Can you swim in Llyn Cwm Llwch?
You can swim in Llyn Cwm Llwch and the lake is easily accessed from the shore. However, the altitude means that the water is very cold, so swimming isn’t recommended outside of summer.
How deep is Llyn Cwm Llwch?
Cwm Llyn Llwch measures between 1-2 acres in size and is between 5-6 metres deep.
More adventure travel guides on A World Over
I hope my guide helps you to enjoy the Llyn Cwm Llwch circular walk. Let me know in the comments about your experience of the hike!
For more Wales adventure travel advice, check out my Wales travel guide. And you can see all my Brecon Beacons guides here.