Carneddau via Cwm Caseg  No ratings yet.

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Route Summary: This walk includes the 2 Washis of Carnedd Llewelyn, Yr Elen

This walk includes the 4 Hewitts of Carnedd Llewelyn, Foel Grach, Yr Elen, Garnedd Uchaf (Carnedd Gwenllian)

This walk includes the 5 Nuttalls of Carnedd Llewelyn, Foel Grach, Yr Elen, Garnedd Uchaf (Carnedd Gwenllian), Gyrn Wigau

17.11 km 907 m

Calculate the time using Naismith’s Rule and factor in your own pace.

Start and Finish:


Check out the businesses nearby for more places to stay and drink.


Remember that we cannot outline every single hazard on a walk – it’s up to you to be safe and competent. Read up on Mountain Safety , Navigation and what equipment you’ll need.

Public Transport: Traveline for UK Public Transport
Parking and Post Code for Sat Nav (where applicable): 

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Carneddau via Cwm Caseg Route Map and GPX Download

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Carneddau via Cwm Caseg Details

There are four valleys to the west of the Carneddau. The northernmost and southernmost aren’t named on the OS maps, but the two in the middle are much larger. Cwm Llafar cuts deep in between the two highest peaks, ending in the steep back wall known as yr Ysgolion Duon (Black Ladders). Strangely, it’s only the other cwm – Cwm Caseg that contains a lake. From this description, “the long valley with the lake above Bethesda” I worked out that my late father had been up here in the sixties. All he can recall is finding a top hat that was completely flat in the middle of the path.

This is an unusual cwm, even disregarding the squashed millinery. There are remains of a large settlement at over 400m, meaning the area must have been populated and farmed, like much of the Carneddau in the past. There’s little here to sustain man now except for a few sheep.  It’s simiar to Cwm Llafar, in that it’s long with a meandering stream. It continues uphill much further though, twisting around Yr Elen before terminating in a hanging valley and lake at Ffynnon Caseg. Today’s walk didn’t visit this highest point of the cwm, from where the only option is Yr Elen’s NE ridge or retreat but in the snow to follow a grassy ridge (Braich y Llyngwn, though possibly yet another OS typo and Llyngwm being the correct name – translated as ridge of the valley of the lake, which makes sense).

Distance, Ascent and Time 18.5km, 1100m, 8 hours

OS Map Required Explorer 017BMC MapLandranger 115

Difficulties Route finding off path. River Crossing

Start / End Gerlan / Bethesda

Facilities Shops, pubs etc in Bethesda.

Public Transport Buses from Bangor, Sherpa from Capel Curig and Caernarfon.

The Route

The walk starts in Gerlan, ideally around SH629 667 which you can reach from most of the streets that branch off the A5. Finding “Glanrafon” is the hardest navigation of the day. Follow this uphill past some houses before soon passing through a gate and onto farmland. The track forks here but take the right fork and follow for a few hundred metres. The driveable track continues right  into a farm at SH636 668, and paths split off left and ahead. Follow the path  directly ahead, and a path continues around a couple of small enclosed fields towards a steep looking gully ahead.


There’s an easy path up this gully, giving your legs a bit of workout before the easier section ahead. The top of this section will leave you above Cwm Caseg with the track a short distance below. Contour the easy grassy hillside to the gate to the east and the obvious track ahead.

As you continue along this initially good track, you soon get swallowed up in the vast cwm. There’s a little quarry on the way, and an ancient settlement which you might find yourself walking through if you miss the right hand fork in the path. The only thing that’s obvious in the settlement is the more modern sheepfold, the rest is barely discernible as the dilapidated remains of walls. Past the sheepfold, the path becomes a little boggy and rough and you need to pick your way and find the driest route until the cwm narrows and you get nearer Afon Caseg at around SH668 665.


You’ll need to pick your way across carefully if the river’s in spate, but if you find that it’s a little deep you can travel a little upstream and you’ll find the river soon narrows. Of course, if you’re not afraid of getting your feet a little wet, you’ll find somewhere easily! The best thing about Braich Maesgwn is the views back towards Clowgyn y Heliwr, and the fact that a bearing due south will take you up safely in mist. Other than that, it’s a total slog.


Gratefully, you reach the skyline and the ridge flattens out. Carnedd Dafydd and Cwm Llafar now dominate the view. You try not to look at the steep scree slope up to Yr Elen. Even worse when that’s partly covered alternately in frozen snow and slushy snow. Zig zagging steeply, this is a testing ascent in snow. It’s soon over. The flat summit of Yr Elen unexpected. The ridge across to Llewelyn looking most welcoming and tiredness in limbs suddenly gone.



A glance down shows us that Ffynnon Caseg is partly frozen, receiving little sunlight in the shadow of Carnedd Llewelyn. The ridge across is an easy ramble in summer, and nothing tricky under snow. There’s a steep pull up to Llewelyn, and once at its top you’ll probably need a compass bearing to find the summit in poor visibility. In snow you can take the chance and follow the footsteps, in the hope that they know where they’re going! Today, they were.


Further fortune is that the owners were long gone, as the shelter on Llewelyn is often full. A group arrived not long after, so timing had been good. Leaving the summit, you’ll need to make sure of your direction with a bearing, but again there were a few footsteps to follow. These weren’t as reliable as the ones we’d followed earlier, and meandered across the slope. It didn’t help that the snow had drifted here, so the descent to Foel Grach was largely in knee deep snow.

Past the shelter, the snow dripping from it’s stones, we contoured around Garnedd Uchaf to descend the Aryg Ridge. This is a normally easy walk, but deep snow drifts hiding either knee twisting holes between boulders, or knee deep bog made it a little more interesting. It’s not the most obvious path in places either, so take care. When the path starts veering to the north, you’ll need to keep an eye out for a faint path to Gyrn Wigau. This is the final point of the ridge, and is probably a Nuttall like these little bumps often are.

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Continuing on the faint path, takes you eventually to the path and sheepfold at SH643 670. Cross the wall at the stile, and cross the short grass that’s easy on the feet at this time of day towards SH639 666 and the stile at the top of the gully you climbed at the start of the walk and retrace your steps to the village.

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