Clydach Gorge main waterfalls walk

Including Pwll Crochan, Pistyll Mawr, Cwm Nantmelyn Waterfall, Waterfall Cave Resurgence Waterfall, Ogof Clogwyn, Devil's Waterfall and Pwll Rhys.

Ability requirements (key)


WARNING: The instructions for finding the start(s) of the route may not currently make sense, as the A465 has been undergoing significant modifications since 2014, due to end in 2018. The description here is based on the proposed final road layout. Visitors may need to use their initiative to find their own way. The main differences will be the new single exit from the A465 at the bottom of the gorge, which was previously two separate exits on either side of the main road.

From Cardiff, take the A470 to the end of Merthyr Tydfil. From Merthyr Tydfil, take the A465 towards Abergavenny, follow it past Brynmawr, and down the Clydach Gorge. At the bottom, take the exit slip road on the left, which is the first exit since the Brynmawr exit (the Brynmawr exit was near the top of the gorge).

For the Blackrock parking, take the road on the left, and follow it back up the valley for 2 km, to a layby parking area with a bus stop on the left (if needed, there is some more space shortly afterwards, in a disused quarry's entrance on the right). SO 2149 1255. Shortly before the layby is a narrow lane dropping steeply on the left, and the walking route starts at the top of this.

For the Clydach South and Gellifelen parking, take the road on the right, passing under the A465 and heading back up the valley. It swings left and climbs to a junction. Turn right, and continue to a fork. For Clydach South parking, take the right fork, and find somewhere convenient to park, preferably near the end of the road, where there is a small parking area. SO 2263 1279. For Gellifelen parking, take the left fork, and follow it uphill, crossing a dismantled railway. When the road hairpins around to the left, continue ahead, around a hairpin to the right, to a junction. Aim down to the right, take the first left, and drop down to a parking area beside some railway tunnels. SO 2149 1213.


WARNING: This route is subject to significant disruption, as the A465 has been undergoing significant modifications since 2014, due to end in 2018. The description here is based on the proposed final road/path layout. Visitors may need to re-invent certain parts of the route. The A465 road crossings may not be in place, forcing the central and lower loops to be followed as separate linear walks, each using the paths on just one side of the A465.

The Clydach Gorge is a strange cross between wild gorge, and urban/industrial influence. There are many paths, but most are not really designed for countryside walks, and are better as utility footpaths for local residents. As a result, there are no convenient routes that take you easily from waterfall to waterfall; if this route seems a little disjointed as a result, that's because it is. The urban influence, however, means that almost all waterfalls have a convenient parking space nearby. As this is intended to be a walking guide, it will offer three parking options with a looping route. I would recommend the Clydach South (Danycoed) parking option, as it means the walk ends downhill, and offers interesting industrial remains to look at afterwards. The central loop of the walk, which contains all of the parking options, is just over 4.5 km. The optional upper section is 4.4 km. The optional detour is 600 metres (700 if you are not also following the upper section). The optional lower loop is 3.8 km. The total walk, including all optional extensions, is 13.3 km.

From Clydach South, take the footpath at the end of the road through the village (where you should be parked), and follow it up the valley. Early on it splits and rejoins, but remains level until it crosses a bridge over a small waterfall, to reach a junction with a steep tramroad on the left. Continue ahead along the remains of a level tramroad to a set of powerful cascades, and then the lower Clydach waterfall (traditionally Pwll Crochan). For this last section, a ditch on the left of the path was once a leat which carried water from the waterfall to the Clydach ironworks. Return to the steep tramroad, and follow it up until it reaches a road beside some lime kilns, and a dismantled railway line. Follow the road up onto the railway line, then take the railway line to the right. Follow it around a long curve (which has several small waterfalls in wet weather on the left side of the cutting) to an embankment and some tunnels, where a stream down to the left has a small cascade. Either go through the right tunnel (you will need a torch), or follow the path around to the right, staying level when it joins a road, to the other end of the tunnels. This is the Gellifelen parking area, where a small waterfall is up beside the tunnels, at the outflow of an adit.

From Gellifelen, there are two optional parts that may be of interest. The upper section takes in a few interesting waterfalls. (The majority of the upper section cannot be followed while the A465 construction work is in progress.) The optional detour takes in three waterfalls. The upper section follows the right bank of the continuing dismantled railway line. After about 700 metres it reaches some houses. Continue ahead. After 750 metres, the path passes over the Pistyll Mawr waterfall, shortly before passing under the Gateway road bridge. It is no longer possible to walk down the roadside to reach the viewpoint. The waterfall itself is guarded by huge crags. Immediately upstream of it, where the river runs underground for about 50 metres, it is possible for experienced walkers to cross the fence and descend the slope and smaller rock outcrop down to the A465. This must be done with great care to avoid the crags. Head a little upstream along the roadside to see the river fall down the waterfall at the pothole entrance to the artificial Coal Tar Cave - be very careful not to fall down it yourself. A little downstream is the resurgence adit, with an impressive 10 metre spout waterfall above it, traditionally known as Pistyll Mawr (before Coal Tar Cave was constructed during the Industrial Revolution, the entire river flowed over this waterfall).

Return to the path and continue along it to reach a roundabout. Turn right onto the pavement, and follow the road to the right around a long curve and over the Gateway bridge over the valley. On the far side, take a path on the right which descends back down to river level. After 200 metres, the path crosses a stream, Cwm Nantmelyn, which has a small cascade just upstream of the footpath bridge. Take a small path beside the stream to a much bigger waterfall, then return back to the footpath bridge. Continue along the path to reach a subway and bridge crossing the A465. (There was previously a man-made waterfall 300 metres down the valley on the northern side of the road, but this will have been destroyed by the new road construction). Cross the A465 and follow the path all the way up to the houses on the dismantled railway line. Turn left and return to Gellifelen.

Back in Gellifelen, the optional detour is to take a path that heads down into the gorge, just past the first building on the way along the dismantled railway line. This descends into the beechwoods, where it bends left then immediately right down some wooden steps. On the other side of the gorge is the Waterfall Cave resurgence waterfall - best seen in winter when there is less foliage. The path leads directly to the Ogof Clogwyn cave entrances, with a short waterfall dropping from its main entrance. A further cascading waterfall can be seen in the main river, just upstream. Return to Gellifelen.

Back in Gellifelen (again), once you are finished with the upper section and optional detour, continue around the central loop. Head along the road away from the railway line and tunnels, taking the left branch when the road forks. After a short distance is a footpath on the left. Follow it down a very steep route beside a stream gully, to the bottom of the gorge (to the left is a path to Pwll y Cwm, a major cave resurgence). The path crosses the Devil's Bridge, over the top of the Devil's Waterfall (traditionally Pwll Cwn), the largest and most powerful waterfall in the valley. The bridge is the best viewpoint - there is no safe way to access it from below. Cross the bridge, and follow the path up to a bridge over the road. Go over it to reach some houses, and follow the lane to the left, steeply up to a proper road at Blackrock. The way on is along the road to the right, while the Blackrock parking layby is to the left. (The Drum & Monkey pub was previously located near the houses, which was a good place to stop for refreshments. However, this was removed to allow the new road construction.)

From Blackrock, take the main village road, heading down the valley. Follow the road for a while, passing some lime kilns on the left. Stay on the road until you reach a stepped path on the right (there is a sloping path on the right a little before this, and in theory that can be used instead, but it was blocked on my last visit). Take the stepped path down to a path junction (where the sloping path rejoins from the right) and turn left to reach a back lane. Follow it for 1 km, until it attempts to join the larger road again. Just before this, take a road down to the right, then a path to the left. This leads over a bridge, back into the Clydach South housing estate. (To the right is a footpath that leads behind the houses, back to the Clydach South parking area, which can be used if you do not plan on following the lower loop.)

Now back in Clydach South, the lower loop begins. Follow the road back out of the estate (to the left if you just arrived over the bridge from Blackrock), and just before some playing fields on the left is a path down to the Clydach Ironworks - the destination for the minerals prepared in the lime kilns, and transported down the tramroads. Cross the bridge over the river at the iron works, turn right onto a track, then branch left onto a footpath which soon passes over a bride over the A465. Follow the path up to a smaller road (the main road that runs through Blackrock), and follow it down to the right. As the road swings right to reach the A465 junction, take a smaller road ahead. When it forks, take the right branch. Just before it crosses the river, take a footpath on the left, which passes through a private-looking driveway gate (signed as belonging to Forge House), and follows a narrow path tucked behind some houses. This leads to a powerful waterfall, Pwll Rhys (aka. Pwll-y-Rhechu/Rhychu), whose best viewpoint is a path on the right immediately after the waterfall. (Optionally at this point, a path up to the left reaches Maesygwartha, where the lane to the left can be used to create a variety of alternative loops back to Blackrock. However, there is no footway, and cars are allowed to drive past at 60 MPH, so this route guide does not use those lanes. Alternatively, the first path on the left in Maesygwartha drops back down to Forge House.) Cross the bridge above the waterfall, and follow the path up to a lane which heads down to the right. Turn right onto the lane (which can be followed back to Forge House if you dislike the main path), then immediately take a path on the left running above the lane, along what was once the old main road. Follow the path to the A465 junction, and continue along the pavement as it crosses the river, then swings right into the Blackrock road, completing the loop. Return to Clydach South.

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More about this area

Whilst every care has been taken in the compilation of this description, neither the author nor his fellow walkers can accept responsibility for loss or injury arising from any errors, omissions or inaccuracies in this description. This description is intended as a guide only, and you should select a route to suit your own abilities, at your own discretion. Ability requirements are a guide only. Route maps are approximated. You follow this description at your own risk.