Region: Black Mountain, Bannau Brycheiniog National Park, Carmarthenshire
Walk summary: This 8.8-mile anti-clockwise circular begins at Llyn y Fan Fach Car Park, visits Llyn y Fan Fach and climbs onto the ridge through Waun Lefrith, Picws Du, Fan Foel and Fan Brycheiniog before descending to Llyn y Fan Fawr and returning across the lower ground. It has 2,126ft of ascent and takes approximately five hours.
| Distance | 8.8 miles / 14.2km |
|---|---|
| Ascent | 2,126ft / 648m |
| Time | 4 hours 50 minutes walking; allow approximately 5 hours |
| Difficulty | Moderate to challenging — a steep ridge climb, exposed high ground and a long return |
| Route | Anti-clockwise circular walk |
| Start and finish | Llyn y Fan Fach Car Park near Llanddeusant |
| Main landmarks | Llyn y Fan Fach, Picws Du, Fan Foel, Fan Brycheiniog and Llyn y Fan Fawr |
| Suitable for | Walkers with suitable fitness, active older children and capable dogs |
The Llyn y Fan Fach, Fan Brycheiniog and Llyn y Fan Fawr circular walk combines two glacial lakes with one of the finest ridge traverses in South Wales. The route’s established identity matters: this is not merely a short visit to Llyn y Fan Fach, but a complete circuit across the Black Mountain to Fan Brycheiniog and Llyn y Fan Fawr.
The terrain is manageable for regular walkers in settled weather, but the ridge can become foggy and extremely windy, while the lower ground can be boggy. Download the GPX before leaving, carry a map and compass, and be prepared to turn back if visibility or wind makes the ridge unsafe.
Llyn y Fan Fach circular map, GPX and parking
- Parking and start: Llyn y Fan Fach Car Park, near Llanddeusant
- GPX: Download the Llyn y Fan Fach circular GPX
- Route apps: View the route on Outdooractive or Komoot
- Facilities: There are no toilets, cafés, shops or other facilities at the start or on the route. Bring all food, water and equipment with you.
The approach to the car park is along narrow rural roads, so drive carefully. In clear weather the ridge is easy to follow, but cloud can remove the visual landmarks very quickly and the lower return has alternative tracks. Save the GPX for offline use rather than relying on mobile signal.
Llyn y Fan Fach and Fan Brycheiniog route description
Begin at Llyn y Fan Fach Car Park and follow the obvious track towards the mountains. Cross the small stone bridge and continue beside the river towards the trout farm, passing through the opening in the wall on its left. The landscape feels remote almost immediately, with the ridge forming a dramatic skyline ahead.
The track continues towards the old pump house and the first of the route’s lakes, Llyn y Fan Fach. This is where the scale of the surrounding escarpment becomes clear and the steep climb to the ridge comes into view.
Llyn y Fan Fach and the Lady of the Lake
Llyn y Fan Fach is closely connected with the Welsh legend of the Lady of the Lake. The story tells of a farmer who married a fairy woman who emerged from the lake, on the condition that he must not strike her three times. When the condition was broken, she returned to the lake with her animals. Their sons became associated with the celebrated Physicians of Myddfai.
The steep climb to Waun Lefrith
Keep Llyn y Fan Fach on your left and take the climbing path onto the ridge. This is the route’s main sustained ascent and the steepest part of the day. Once the height is gained, the ridge becomes much flatter and gives superb views back over the lake—when the cloud allows.
Picws Du, Fan Foel and Fan Brycheiniog
Follow the high ground anti-clockwise from Waun Lefrith towards Picws Du, then continue to Fan Foel. Llyn y Fan Fach gradually disappears behind you while the eastern part of the escarpment opens ahead.
From Fan Foel, continue to Fan Brycheiniog, the route’s highest summit at approximately 802 metres. Its trig point and stone shelter provide an obvious landmark. Llyn y Fan Fawr is now visible below, forming the third major landmark of the anti-clockwise circuit after Llyn y Fan Fach and Fan Brycheiniog.
Descending to Llyn y Fan Fawr
Continue around the ridge and follow the GPX carefully onto the descent to Llyn y Fan Fawr. The descent and lower ground require particular attention in mist because alternative paths can be difficult to distinguish. Once beside the lake, pass around it with the water on your left before beginning the long return west.
The return to Llyn y Fan Fach Car Park
The return from Llyn y Fan Fawr is nearly four miles across the lower ground beneath the ridge. It can feel longer than expected, and boggy conditions may slow progress. The whole escarpment remains visible to your left in clear weather, giving a superb perspective on the route you have just completed.
We met a walker who had lost her way in this section and walked back with her and her dog. That experience reinforced why downloading the GPX route before setting out is important. Continue until you regain the outward track near the trout farm, cross the small bridge and descend to the car park.
Llyn y Fan Fach circular walk practicalities
- Parking: Start at Llyn y Fan Fach Car Park near Llanddeusant. The approach uses narrow rural roads, so allow extra time and drive carefully.
- Difficulty: Moderate to challenging. The steep climb onto the ridge is the principal physical test, followed by a long circuit and lower return.
- Navigation: Straightforward in clear weather but potentially confusing in fog, especially around the descent and lower paths. Carry offline GPX navigation, a map and compass.
- Underfoot: Track, mountain path, exposed ridge and boggy lower ground. Wear waterproof boots with dependable grip.
- Weather: Fog and powerful wind can make the ridge much more serious. Check a mountain forecast and be prepared to turn around.
- Children: Best suited to active older children who can manage the distance and ascent. It is not an appropriate full circuit for very young children.
- Dogs: Suitable for fit dogs comfortable with a full mountain day. Keep dogs under close control near steep ground and whenever animals are encountered.
- Facilities: There are no facilities at the car park or along the route. Carry sufficient food, water and emergency supplies.
Preview the route in 3D
Watch the route before setting out to understand the ridge circuit, Fan Brycheiniog and the long return from Llyn y Fan Fawr.