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Carneddau From Bethesda via Cwm Caseg

By Dave Roberts   

on May 29, 2020    3/5 (1)

Carneddau From Bethesda via Cwm Caseg

Route Essentials

Route Summary

See the end of the article for local information about parking, public transport facilities, pubs and cafes.


16.76 km


929 m


7 hours

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

Start Location

Gerlan / Bethesda


Strenuous Walk


Route finding off path. River Crossing needs to be tackled.

Weather Forecast:

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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. 

Carneddau From Bethesda via Cwm Caseg Ordnance Survey Map and GPX File Download

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Carneddau From Bethesda via Cwm Caseg

There are three valleys to the west of the Carneddau. The northernmost isn’t named on the OS maps, we know it as Cwm Ffrydlas, but the other two are much larger. Cwm Llafar cuts deep in between the two highest peaks of Carnedd Llywelyn and Dafydd, 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 similar 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).

Carneddau From Bethesda via Cwm Caseg Route Description

1 The walk starts in Gerlan, ideally around the road junction at SH633 662, which you’ll probably need to walk to from some point further down as parking is limited, but there is a bus service that almost reaches the junction. The google maps link is here – and you should be able to reach this point easily from the village. Head up this narrow lane for around a kilometre and you’ll reach the main track into Cwm Caseg

2 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.

3 You’ll need to pick your way across carefully if the Afon Caseg is 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.

4 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.

5 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.

6 The ridge across to Carnedd Llywelyn 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 at weekends. A group arrived not long after, so timing had been good.

7 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.

8 Once past the shelter, the snow dripping from it’s stones, you need to contour 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. There are often upright stones that you can use to navigate this path, which can be hard to spot in the first place and especially so under snow. It does become clearer the lower you go, with the track eventually becoming a land rover track. The descent is long, and you can choose to head over towards Bera Bach and over Drosgl if you want to bag a few more summits.

9 Eventually, the good track starts veering to the north, but you’ll need to keep an eye out for a faint path to Gyrn Wigau dead ahead. This is the final point of the ridge, and is probably a Nuttall like these little bumps often are.

10 From Gyrn Wigau, a faint path can be followed across easy grassland that leads you to the lane you started on earlier (end of step 1). You’ll need to cross the wall when you reach it, and continuing on the same path you should end up at the end of the lane as previously mentioned.

Local Information and Recommended Maps and Guidebooks

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 Gyrn Wigau, Carnedd Llewelyn, Foel Grach, Yr Elen, Garnedd Uchaf (Carnedd Gwenllian)

Route Start Location: Gerlan / Bethesda

16.76 km 929 m 7 hours

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

Activivity Type: Strenuous Walk

Summits and Places on this Route


Shops, pubs etc in Bethesda.


Route finding off path. River Crossing needs to be tackled.

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.

Parking :

Limited roadside parking – streets are narrow and consideration is needed for the residents.

Public Transport:

Buses from Bangor, Sherpa from Capel Curig.

Traveline for UK Public Transport

Recommended Maps


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Dave Roberts

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