North Wales · Waterfalls · Slate history
Cwmorthin Circular Walk The Lost Waterfalls & Slate Kingdom Trail
A proper mountain adventure above Blaenau Ffestiniog, climbing beside waterfalls to a hidden lake before crossing one of Wales’s most atmospheric abandoned slate landscapes.
Recorded circular route · Independently researched · Safety guidance included
Plan the walk properly
The full recorded route, ready for the mountain.
Before you leave home
The useful details, without the searching.
Starting and finishing above Tanygrisiau.
Rock, loose slate, grass, mud and wet ground.
Use Tanygrisiau or Blaenau Ffestiniog first.
No pushchairs or wheelchairs on the full route.
Livestock graze throughout the landscape.
Old quarry tracks create misleading junctions.
Wild scenery, photography and slate ruins.
Still steep and rocky, but avoids the upper loop.
Why this walk stays with you
A hidden valley with two completely different stories.
The first belongs to the water. A rocky track climbs beside the Afon Cwmorthin, passing cascades and plunge pools before the landscape suddenly opens beside Llyn Cwmorthin.
The second belongs to the people who worked here. Cwmorthin Quarry operated from around 1810 until 1939, leaving old tramways, inclines, terraces, mill remains and a vast underground network beneath the mountain.
The Ffestiniog slate landscape forms part of the wider Slate Landscape of Northwest Wales UNESCO World Heritage Site. It is compelling precisely because it has not been sanitised. Treat the ruins as historic scenery, not a playground.
Seven moments worth slowing down for
Water, stone and a landscape slowly reclaiming itself.
Cwmorthin waterfall climb
A steep rocky beginning beside several cascades and a deep ravine.
Llyn Cwmorthin
A dark mountain lake held beneath steep, slate-grey hills.
Cwmorthin Terrace
Haunting remains of the community that lived and worked in the valley.
Quarry mills and inclines
Fragments of the machinery and transport system that once moved the slate.
The upper slate landscape
Lonely tracks, spoil heaps and wide views beneath the Moelwynion.
Stone bridges and streams
Small crossings that join the valley’s natural and industrial stories.
The return to Tanygrisiau
Descending water, open valley views and the final careful walk back.
Follow the recorded line
The walk, stage by stage.
These directions explain the character of each section. They do not replace the interactive track, an offline map or your own judgement when conditions change.
Car park to the waterfalls
Go through the access gate and take the obvious rocky track climbing into Cwmorthin. Keep to the established route on the right-hand side of the ravine. The first climb is short but steep, with loose and wet rock underfoot.
Follow the water uphill
Continue past the cascades and plunge pool. An old crossing shown in some descriptions is no longer usable, so remain on the established side of the watercourse rather than attempting a shortcut.
Llyn Cwmorthin and the lower quarry
As the gradient eases, the lake and first quarry remains appear. Follow the clear track beside the water and stay back from the edge in strong wind. View the ruins only from safe, established ground.
Cross the slate kingdom
Follow the recorded circuit beyond the lake. Numerous tramways and workers’ tracks can look like the main route. Check every major split and never follow a line into an adit, tunnel, excavation or fenced working.
Complete the upper loop
The route bends through rougher upland terrain before turning home. Expect wet patches even after dry weather and take care wherever loose slate covers the path. In mist, stop and confirm the recorded line.
Return beside the lake
Rejoin the lower valley route and descend past Llyn Cwmorthin. Take particular care on the waterfall track: the same stone that felt manageable uphill can be slippery beneath tired legs.
The practical bits
Parking, facilities and the sensible shorter option.
Parking and arrival
The small Cwmorthin car park sits at the top of a narrow lane. Spaces are limited and there is no guarantee of parking. If it is full, turn around safely and use a lawful lower space near Tanygrisiau. Never block gates, homes, passing places or emergency access.
The Ramblers notes additional parking beside the lane leading up from the Lakeside Cafe. Check every sign when you arrive because arrangements can change.
Facilities and the shorter walk
There are no dependable toilets, bins, water points or refreshments on the mountain route. Bring everything you need and take all rubbish home.
For a shorter day, visit the waterfalls, lower quarry and Llyn Cwmorthin as an out-and-back walk. It remains steep, rocky and unsuitable for wheels, but avoids the exposed upper circuit.
This landscape is not sanitised
Beautiful, historic and genuinely hazardous.
Unprotected drops, hidden workings, loose slate and rapidly changing mountain weather are all real risks. If conditions feel wrong, turn back.
- Check the Met Office mountain forecast and available daylight.
- Never enter mines, tunnels, adits, shafts or unstable buildings.
- Keep well back from quarry edges, spoil tips and deep water.
- Carry an offline route, detailed paper map and compass.
- Pack food, water, warm layers, waterproofs, torch and charged phone.
- Tell someone your route and expected return time.
- Keep dogs on a short lead around livestock and wildlife.
- In an emergency call 999, ask for Police, then Mountain Rescue.
Useful kit for this terrain
Pack for wet stone, loose slate and fast-changing weather.
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Turn the walk into a North Wales break
Stay near the mountains. Give yourself another day.
Search around Blaenau Ffestiniog, Porthmadog, Betws-y-Coed or the wider Eryri area. Move the map to compare current locations, prices and availability.
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Check before travelling
Everything worth checking before you set off.
Cwmorthin Circular Walk FAQs
How long is the Cwmorthin circular walk?
The recorded circular route is 10.38 km (6.45 miles), with 353 metres of ascent. Allow around 4-5 hours so you have time for careful navigation, photographs and safe stops.
How difficult is the Lost Waterfalls & Slate Kingdom Trail?
It is a moderate mountain walk with steep rocky tracks, loose slate, wet ground and exposed sections. It is unsuitable for pushchairs and wheelchairs.
Where do I park for Cwmorthin?
The route starts at the small Cwmorthin car park above Tanygrisiau. Spaces are limited. If it is full, use a lawful lower space and never block gates, homes, passing places or emergency access.
Can I enter the abandoned slate mines?
No. Never enter tunnels, adits, shafts, excavations or unstable buildings. Hidden drops, rockfall, flooding and collapses can be fatal.
Can I take a dog on the route?
Livestock graze in the area, so dogs must be kept on a short lead and under close control. Some organised walks in this landscape advise that their particular route is unsuitable for dogs.
Is there a shorter Cwmorthin walk?
Yes. You can make an out-and-back visit to the waterfalls, lower quarry and Llyn Cwmorthin, turning back before the upper loop. The approach is still steep, rocky and unsuitable for wheels.
Are there toilets or cafes on the walk?
There are no reliable facilities on the mountain route. Use facilities in Tanygrisiau or Blaenau Ffestiniog and carry all food, water and rubbish with you.
Is Cwmorthin part of a World Heritage Site?
Cwmorthin sits within the Ffestiniog slate landscape, part of the Slate Landscape of Northwest Wales UNESCO World Heritage Site.
When is the best time to do the walk?
Choose a clear, settled day with enough daylight. Avoid high winds, thunderstorms, heavy rain, flooding, snow, ice and poor visibility unless you have the experience and equipment for those conditions.
Do I need an offline map?
Yes. Save the recorded track offline and carry a detailed paper map and compass as backup. Old quarry tracks can make the correct route difficult to identify in mist.
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