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SW Nantlle hills & cwms 2 days / 10 miles (16km)

OS Route Map → Map Route file →

Date: 15 Aug 2016
Start / Finish: Nebo. Good roadside parking on Ffordd Nebo, SH477505.
Maps: Explorer OL17 Snowdon & Conwy Valley or Harvey Superscale Snowdonia.

Day 1Mynydd Graig Goch to Craig Cwm Silyn4.8miles / 2105 feet (7.7km / 642m)
Day 2Cwm Afon Craig-las & Cwm Silyn5.0miles / 570 feet (8km / 174m)
Ascending Mynydd Graig Goch

A 2-day circuit from Nebo of the mountains and little trodden cwms in the south-western half of the Nantlle ridge, a region of Wales we last visited thirteen years ago.

In our quest for new pockets of territory to explore at a slackpacking pace, we approached Mynydd Graig Goch on its north-western ridge via Llyn Cwm Dulyn, while the focus for the second day was the undoubtedly little frequented area below the crags of Craig Cwm Silyn, including the corrie lake with its companion and some nameless pools on the higher ground between Cwm Silyn and Cwm Afon Craig-las.

This short spell of warm and sunny August weather was the perfect time to experience the vibrant colours of the heather and bog vegetation, particularly on the second day below the crags when picking our way through the mixture of boggy ground, fallen boulders and heather that make this a superb fragment of wild Wales.

Day 1 - Mynydd Graig Goch to Craig Cwm Silyn

We took the narrow lane SE from the road junction in Nebo to the right-angled bend and continued along a track to Llyn Cwm Dulyn where the western extremity was fenced off for engineering works. This gave the lake the air of a man-made reservoir, but once beyond the fencing the view across the water towards Craig Cwm Dulyn was excellent.

We walked along the shoreline as far as the fence and crossed to start the initially steep climb of the NW ridge of Mynydd Graig Goch following a discernible path. Above the first heathery crags the rocky tors of the summit area soon appear in the distance, the first high tor lying on the western side of the cross wall. A new ladder stile immediately beyond gives access to the elongated rock and grass plateau of the 610m summit with a 606m subsidiary rise at the far end. There are grand views out to the Yr Eifl group on the Lleyn Peninsula and ahead to Garnedd-goch.

Llyn Cwm Dulyn
Llyn Cwm Dulyn (15 Aug 2016__09:06:22)
Mynydd Graig Goch summit area
Mynydd Graig Goch summit area (15 Aug 2016__11:30:32)
The Hebog ridge from Mynydd Graig Goch
The Hebog ridge from Mynydd Graig Goch (15 Aug 2016__11:49:36)

An easy gentle descent on grass to Bwlch Cwmdulyn lies ahead and we picked up a thin path part way down. Garnedd-goch looks considerably mightier than we remember it, although on our last visit we were in descent. Just beyond the bwlch a difference of opinion is apparent at a fork in the path: we followed the left path along the public right-of-way to the wall and ascended on its north-western side to the squat trig point and wall junction.

Despite the breeze the enclosed summit area was teeming with dense clouds of those quite large black insects that emerge in vast numbers in mid-August and that we have yet to identify, and we made a hasty departure for more open ground to rest and take a bite to eat.

Garnedd-goch
Garnedd-goch (15 Aug 2016__12:52:15)
The Hebog ridge from Garnedd-goch
The Hebog ridge from Garnedd-goch (15 Aug 2016__14:41:47)

Approaching Craig Cwm Silyn we veered leftwards for a view of Llynnau Cwm Silyn from Craig yr Ogof and to scout the ground for a pitch. Until now the area had been deserted but we saw a few people on the summit ahead. There were good views to the northern section of the ridge, Mynydd Tal-y-mignedd and Mynydd Mawr.

Returning to our pitch spot, the breeze had totally disappeared but strangely there were no midges at all, just a small contingent of the black insects helping with every stage of the pitch.

Mynydd Mawr from Craig Cwm Silyn
Mynydd Mawr from Craig Cwm Silyn (15 Aug 2016__14:42:28)
Llynnau Cwm Silyn from top of Craig yr Ogof
Llynnau Cwm Silyn from top of Craig yr Ogof (15 Aug 2016__15:47:40)
Mynydd Tal-y-mignedd
Mynydd Tal-y-mignedd (15 Aug 2016__16:10:53)
Pitch on Craig Cwm Silyn
Pitch on Craig Cwm Silyn (15 Aug 2016__17:14:18)

Day 2 - Cwm Afon Craig-las & Cwm Silyn

Later in the night the wind returned just as suddenly and with enough strength in its gusts to rock the tent at times. Striking camp and gaining the summit once more, the low early sunlight gave excellent views of the landscape as always.

View to Garnedd-goch and Yr Eifl from Craig Cwm Silyn
View to Garnedd-goch and Yr Eifl from Craig Cwm Silyn (16 Aug 2016__08:28:31)
Early light on Craig Cwm Silyn looking SE
Early light on Craig Cwm Silyn looking SE (16 Aug 2016__08:32:55)
Craig Cwm Silyn summit area
Craig Cwm Silyn summit area (16 Aug 2016__08:40:04)
Early light on the NE Nantlle ridge
Early light on the NE Nantlle ridge (16 Aug 2016__08:45:11)

Remembering that the path lay to the west of the direct descent line to avoid the crags of Craig Pennant, we slowly picked our way down the northern face and saw a sight we have never before encountered in a mountainous region: a huge number of swallows zooming around the crags, so many that there were several in frame at any one time when taking a photo. Surely the emergence of those black insects on the same trip is no coincidence. [Edit: checking our log, the last time we noted the black insect swarms was in the Hirnants on 15th. August 2005 - exactly the same day as this backpack].

Arriving at the contour of Bwlch Dros-bern, we continued the descent on steep grass to join the stream that plunges into Cwm Afon Craig-las. Rounding the corner into the cwm, the wet expanse of the 'mignedd' presided over by Mynydd Tal-y-mignedd appears, the route forwards lying around its edge below the crags.

The whole section from here to Cwm Silyn is the almost untrodden quintessential wild Wales: slow going, sometimes tough and often wet, but not really difficult, full of character and highly rewarding in these conditions on so many levels. The rockfall from the crags presents skew rocks and boulders of all sizes at some points, the largest ones accumulating little pools of their own. One very large boulder sits astride a streamlet with its own micro-cave of bog flora beneath.

Craig Pennant with swallows
Craig Pennant with swallows (16 Aug 2016__09:10:13)
Descending from Bwlch Dros-bern
Descending from Bwlch Dros-bern (16 Aug 2016__11:17:52)
Head of the 'mignedd' below Mynydd Tal-y-mignedd
Head of the 'mignedd' below Mynydd Tal-y-mignedd (16 Aug 2016__11:48:01)
View back across the 'mignedd' below Mynydd Tal-y-mignedd
View back across the 'mignedd' below Mynydd Tal-y-mignedd (16 Aug 2016__12:16:59)
Sculpture-esque fallen boulder in the mignedd
Sculpture-esque fallen boulder in the mignedd (16 Aug 2016__12:21:06)

At the far end of this cwm, surprisingly, is a ladder stile, and just beyond on the right of the downflowing stream is a low heathery rib with a grassy edge - this gives an easy though briefly steep ascent to the boggy saddle separating this cwm from Cwm Silyn. We arrived at the first of the two reedy pools and continued on its north side, the spongey marsh parched enough to keep us dryshod, with the brilliantly colourful heathery crags above. The second pool had more open water and formed a fine foreground to the broken craggy face.

Route up outflow stream to the pools on the saddle
Route up outflow stream to the pools on the saddle (16 Aug 2016__12:33:59)
Second pool on the saddle
Second pool on the saddle (16 Aug 2016__13:22:09)
Autumn colours of the heather and bog vegetation
Autumn colours of the heather and bog vegetation (16 Aug 2016__13:27:40)

Spotting a very vague line at the foot of the crags, we crossed to the south side of the second pool and it was a thin sheeptrod heading west towards the predominant heather. Once in the heather, this very thin overhung path is invisible unless you are actually on it, but it continues reliably and unerringly all the way down to the narrow neck between the two lakes of Cwm Silyn.

The corrie lake soon comes into view and is a splendid sight, the northern shore giving a fine view over the water to Craig yr Ogof.

Llynnau Cwm Silyn corrie lake
Llynnau Cwm Silyn corrie lake (16 Aug 2016__13:33:15)
Llynnau Cwm Silyn corrie lake & Craig yr Ogof
Llynnau Cwm Silyn corrie lake & Craig yr Ogof (16 Aug 2016__13:48:13)
Llynnau Cwm Silyn northern lake
Llynnau Cwm Silyn northern lake (16 Aug 2016__13:51:06)

We easily stepped across the narrow water channel between the lakes on protruding rocks today - maybe not so easy after a wet spell. We ascended gently north-westwards over rocks and grass to locate a skeletal ruined building where a track departs to meet a wall coming up from the northern end of the lake. From here an excellent track leads westwards to the roadhead at Maen-llwyd. Our return route was a short way along this road via the public bridleway at Maen-y-gaseg (SH492512) and the footbridge over the Afon Ddu to the footpath heading south to emerge on the minor road back to Nebo.