Summary: The Black Mountain range (Mynydd Du) in the Brecon Beacons National Park can be reached via a circular walk, involving some occasionally challenging navigation.

Despite ambitious plans to tackle the Black Mountain range (Mynydd Du) area in the Brecon Beacons, including Sinc Giedd and Bannau Sir Gaer, I’m not expecting the most favourable weather in late October. But I’m in the UK for some meetings, and the timing is outside my control. After some discussion via email some weeks prior with a London-based friend, we settle on the Brecon Beacons as the best choice for a more challenging day-walk. I’m picking up a car the day before for the drive from London, and we’re staying in The Wellington hotel in Brecon on the Friday night, so we can make an early start the following day.

The weather turns out to be perfect – sunny but cool and with no rain in sight, as we set out around 8:30am from Brecon for the half hour drive to the start of our walk in Glyntawe in the Afon Tawe valley on the A4067. Which is good, as our guide book suggests: “This walk should only be attempted in good visibility…”.

We leave the car near Saint John the Baptist Callwen church, and walk back along the road, crossing the River Tawe on the Pont Haffes bridge by foot.


The path starts at a gate on the opposite side of the road to the church, crossing a stile and roughly following the Nant Haffes (one of the steepest rivers in Wales) upstream to Carreg Haffes Farm. After a bit less than a kilometre from the start of the path, we cross the river and climb up the ridge.

The path is clearly defined as it gains altitude… but after another kilometre or so we realise the well-marked trail is not going in the right direction!


So, we set-off across the ‘karstic’ landscape, which consists of shake holes and outcrops of Carboniferous limestone in what is roughly the right bearing (there’s no longer a marked track, although for some time we are following a rough stone fence as we head in a generally westerly direction).DSC02161-LR

We pass by numerous “shake holes” which are characteristic of this area: they are depressions caused by the top later of Millstone Grit (coarse-grained sandstone of Carboniferous age) being undermined by the collapse of cavern roofs in the underlying Carboniferous limestone.


After another kilometre or so (we’ve now walked about 3.1km or 2 miles from the car) we make another course correction, and swing north. It’s fairly easy walking despite having no marked trail, although there are a few stream crossings and boggy sections that we need to traverse.

We eventually reach the southern end of Fan Hir, and climb up the side of the ridge to join the marked path that follows the ridge up to the top. (We’ve realise that we’ve gone much too far north –  we should be returning to our car this way – so we decide to “reverse” the circuit we are doing and continue up Fan Hir and back via Bannau Sir Gaer).

Fan Hir means “long peak” in Welsh, as the peak is about 4km (2.5 miles long) with a steep drop on the eastern side (below).


Looking back to the south from the ridge, the A4067 and the valley where we started is in the distance. After three and a half hours of walking, it’s nice to know exactly where we are for a change 🙂


From here we have some relatively easy walking for a while, as we follow the ridge along Fan Hir and then up to Fan Brycheiniog (the highest peak at 2633 feet or 802m in the Black Mountain), with Llyn y Fan Fawr (“lake of the big peak”) to the right.


We reach the Trecastle trig point on Fan Brycheiniog, the third highest summit in South Wales, at about 1:15pm, after exactly four hours walking (covering about 11km, or 6.8 miles), so we are doing OK.


Having reached the highest point on our walk, we follow the ridge-top in a westerly direction, descending a little before a steep climb up to Bannau Sir Gaer, a subsidiary summit of Fan Brycheiniog.


The peak overlooks lake of Llyn y Fan Fach in the cwm (“a steep-sided hollow at the head of a valley”) below, with the summit on the edge of an escarpment. There are extensive views to the north and west, with Waun Lefrith (the lower summit of the Bannau Sir Gaer / Carmarthen Fans) situated to the west and the Cambrian Mountains beyond.


Following the ridge we reach the summit of Waun Lefrith. From here we can can see the Beacons Way heading north as far as the eye can see… but we need to head south to circle back to where we started.

There’s no obvious track, so we take a rough bearing and head down the side of the ridge (reviewing our route later, it seems we’ve gone too far west, rather than going directly south down the mountain). Although we occasionally find some distinct tracks, we are mostly walking off-track as we head initially west, then south and finally east in broad circuit, crossing the Alon Twrch stream as we head back towards the car.


It’s a beautiful afternoon and while the terrain is not difficult, walking for over 10km (6 miles) without a path and through some boggy areas is getting tiring… We’re not at all displeased to reach one of the marked routes as the sun begins to set, re-joining the path we started on earlier in the day.


We finish the walk as the sun sets, getting back to our car around 6pm (we re-trace our steps for the last kilometre or so).


It’s been a great walk – very scenic and with some challenging route-finding. We have somehow managed to turn our circuit into a “figure 8” walk, with the majority of our 26km (16m miles) walk being off-track. I’m not sure if there was a track and we missed it – or whether there is no distinctive trail to follow.

Regardless, we’ve enjoyed our nine hours of hiking. Unfortunately, due to an accident on the M4, it takes almost nine hours to return the car to Hertz at Heathrow…

Accommodation near the Brecon Beacons

We staye at The Wellington in Brecon, which is located within the Brecon Beacons National Park. It’s fairly central to many of the walks in the Brecons Beacons (especially those in the Black Mountain area).

More information on Black Mountain and the Brecon Beacons

Subscribe via Email

Enter your email address to subscribe to Hiking the World, and receive notifications of new posts by email. (A hike is added every 1-2 weeks, on average.)

Join 1,187 other subscribers

Featured Guides

A list of hiking guidebooks I've researched, purchased and used. Each is rated based on it's overall value.


Leave a Reply