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Walk to Llyn Llywelyn and Cwm Trwsgl from Rhyd Ddu

By Dave Roberts   

on June 20, 2021    5/5 (1)

Walk to Llyn Llywelyn and Cwm Trwsgl from Rhyd Ddu

Further Details

Route Summary:

A mid-level walk from Rhyd-ddu that takes in spectacular mountain scenery, woodlands and a lake.

Route Start Location: Rhyd Ddu

12km 430m allow 4 hours

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

Activivity Type: Moderate Walk

Summits and Places on this Route


There’s a decent pub in Rhyd-ddu that has a wide selection of decent ales and food, as well as a tea room. Toliets can be found at the car park


The easier option is straightforward enough, with navigating forestry roads being the hardest part. The harder section is rougher and passes very close to an open quarry at one point – so care is needed.

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 : LL54 6TN

Plenty of parking the car park (paid for) – usually a good bet on a busy weekend.

Public Transport:

Sherpa Buses and WHR to Rhyd Ddu.

Traveline for UK Public Transport

Weather Forecast:

Check out our Best Mountain Weather Forecast?

Recommended Maps


Walk to Llyn Llywelyn and Cwm Trwsgl from Rhyd Ddu Ordnance Survey Map and GPX File Download

Download file for GPS

Walk to Llyn Llywelyn and Cwm Trwsgl from Rhyd Ddu

Most walks from Rhyd-ddu are mountain walks, with the exception of the Lon Gwyrfai route to Beddgelert. This walk uses this excellent easy track, along with forestry tracks and an optional diversion around rugged hills and old quarries to provide a mid level excursion that’s full of interest. Beware that while the forestry section is reasonably easy under foot, sections 4-7 which skirt around the rocky peak of Gyrn towards Bwlch Cwm Trwsgl and back down into Beddgelert Forest is a totally different proposition that’s rough underfoot and requires some route-finding in order to complete safely. You can, however, easily avoid this section.

1 The walk starts off at the Rhyd Ddu Snowdon car park. Cross the road and you’ll join the Lon Gwyrfai trail that’s waymarked for Beddgelert. Follow this across the moorland, where it veers left around a cottage and over a wide footbridge. Just beyond this, the route forks. Take the right hand path which brings you confusingly to a road and layby.

2 Take the path now to your left that approaches the hills directly ahead, with the rocky ridge dominating the view being Mynydd Drws y Coed which is part of the Crib Nantlle Ridge scramble. The path is indistinct in places, but contours low along the hillside, heading towards the forestry in the distance. Take care not to head up the Nantlle Ridge, which should be pretty obvious if you find the path going steeply uphill. Be careful as the path crosses the stream that cascades down Cwm Marchnad as there is a minor crossing here – it only requires a step or two but does have a bit of a drop to the left! The path also thread around and is becoming badly eroded, so try and keep to the path itself rather than making it any wider.

Looking back towards Rhyd-ddu from the bridleway

3 On entering the forest, there’s now an excellent footpath. This used to be a boggy morass, but recent improvement means this is one of the better sections on the walk. After a few 100m, you’ll join a forestry track. This section can be complicated as there are a number of junctions as well as the map being slightly inaccurate. You can either head right and immediately left (or head straight ahead through the woodland on a narrow path. They both bring you onto an ugly concrete bridge that has an old wooden sign denoting Cwm Ddu. Continue on this trail for 250m, where the trail branches again. Turn right here (for the easier option, turn left – and see step 4a below). Note – keep an eye out for blue bridleway markers – as these also denote the way but aren’t always obvious.

4 Immediately after turning right you’ll spot the bridleway into the forest on your left. This path pulls uphill for around 1km, opening up nearer the top with breath-taking views across Cwm Du to Crib Nantlle (Nantlle Ridge) and back towards Yr Wyddfa (Snowdon). The route eventually levels out as you reach Bwlch-y-ddwy-elor. It may be worth considering at this point that this is the pass of the two biers – which isn’t a pair of refreshing beverages but a frame on which a coffin or corpse is carried. The pass is so-called as bodies used to be carried over from one side of the pass and would be swapped here from one bier to the other to continue on their journey to be buried.

Looking towards Cwm Pennant from Bwlch-y-ddwy-elor

4a For the easier option – turn left and continue on the forestry track, where it soon branches off continue right and then left and downhill at the next junction. Follow the trail downhill, before taking the left hand junction which brings you to Llyn Llywelyn and re-join the main walk ar section 8.

5 The section from Bwlch-y-ddwy-elor into Cwm Trwsgl can be tricky to follow, in that it has a number of paths that can be followed and it is far too easy to find yourself further down than you need to be. Keep to the path that veers faintly towards the middle of the valley rather than veering right on the clearer path, which takes you past one quarry (which you’ll see to your left) and finally towards a ruined building and a larger open quarry pit to your left.

6 From the ruin – you should be able to see an open quarry to your left, the footpath keeps to the right of this and climbs over the shoulder. The open quarry is quite treacherous, with the edges lined with heather making the edge itself difficult to determine – so keep well clear! To your right down the valley, you should be able to spot a small quarry reservoir and an extensive view down into Cwm Pennant. Continue along the track, that undulates and meanders its way towards Bwlch Cwm Trwsgl and can be faint in places. It can be easy to get distracted as the view ahead is dominated by the sheer cliffs of Moel Lefn and the jagged ridge of Craig Cwm Silyn behind you.

The path levels out at the bwlch, and appears to cross a section of pure bog. A reasonably dry path does skirt around to the left, with the option of keeping behind the stone wall taking the driest route. Just beyond this the path crosses the high point of the pass and towards cleared forestry. Cross the stile left (the good path right is the descent route from Moel Hebog) and a sketchy path quickly joins the forestry tracks.

7 The walk is now quite straightforward underfoot, but the forestry tracks can be a pain to navigate. Follow the forestry road left, pulling slightly uphill before joining another track, where you turn right and then left at the next junction. This takes you downhill towards Llyn Llywelyn, which is a perfect point to stop.

8 From Llyn Llywelyn, continue on the forestry track ignoring the first junction and continuing onward. At the next junction, again continue onward – but bear in mind that the continuing track becomes more of a wide path than a road. Keep an eye out for the narrow path that leads off left at SH569 498, which can be a bit wet in places but bring you directly out on the Lon Las Gwyrfai. Don’t worry if you miss this path, as you can continue on the initial path and join the Lon Gwyrfai a bit further along. With this being slightly further, but easier going there’s not much to choose between them.


9 On the Lon Gwyrfai, turn left where the trail crosses an old pack horse bridge (Pont Rhyd Ceffylau). The trail continues, veering left past a farmhouse and a log cabin, before joining a longer gravel road that provides access to the nearby car park (an alternative starting point for the walk – especially as the parking here is free). You are also parallel to the Welsh Highland Railway, and you may be lucky enough to spot the train in action. The gravel road eventually reaches the main road. Don’t be tempted to take a short cut along the road, there is no pavement and it is narrow.

Aran Circuit (12 of 28)

10 From the main road, the route back is waymarked – Rhyd Ddu 2.6km. Follow the route over the railway, keeping an eye out for trains, and uphill through the forestry. Turn right at the first and second junctions, both clearly way-marked. 1.2km from the start of the section, you’ll find a gate and the track leaves the forestry.

11 The final section is one of the most scenic as the route undulates through trees and along the shore of Llyn y Gader past the remains of old quarries. The views speak for themselves, and the trail from here is straightforward to follow back to the Rhyd Ddu Snowdon car park from where the walk started. 

Dave Roberts founded Walk Eryri in 2004, with the aim of providing routes that are off the beaten track. Walk Eryri is now part of Mud and Routes which continues to provide more off beat routes and walks in Snowdonia and beyond. Dave has been exploring the hills of Eryri for over thirty years, and is a qualified Mountain Leader. Dave also established Walk up Snowdon, Walk up Scafell Pike and Walk up Ben Nevis just to mention a few.

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