Map & Elevation
About this Route
This GPX climbs Arenig Fawr by Llyn Arenig Fawr and Y Castell, returning the same way. It covers 13.2 km with about 614 m of ascent and usually takes 5 to 7 hours. The approach track is clear, but the mountain beyond the lake is remote, wet and only faintly pathed.
Follow the access track towards Llyn Arenig Fawr, passing the small bothy near the water. Continue around the lake and onto the southern approach, climbing rough grass and peat towards Y Castell. The ridge becomes stonier as it rises towards Arenig Fawr's broad summit at 854 m. A memorial commemorates American airmen killed when a B-17 crashed on the mountain in 1943; treat the site with respect and leave all wreckage undisturbed.
Return past Y Castell and the lake by the same route. This GPX does not continue to Arenig Fawr South Top or make a wider ridge circuit. The upper path is indistinct and an old boundary fence may provide only a partial handrail. Cloud, bog and wind are common, so carry a map and compass and keep enough time for the long approach track.
There are few identifiable paths on Arenig Fawr, though an old boundary fence helps mark part of the route.
Arenig Fawr guide
Route Waypoints
Start from the recognised route access and use only permitted parking. Keep farm and track entrances clear.
Follow the main track towards Llyn Arenig Fawr, ignoring side tracks into fields or quarry ground.
Pass the small bothy near the lake. Leave it clean, do not rely on it being available and follow the Bothy Code.
Continue around the reservoir on the GPX line. Ground becomes wetter as the clear track fades.
Climb rough grass and peat towards the rocky ridge. Use the fence only as confirmation of your route.
Continue over stones and broad ground. In cloud, take a bearing for the summit and return.
Reach the 854 m summit and memorial area. Do not remove or disturb any aircraft remains.
Retrace Y Castell, Llyn Arenig Fawr and the approach track to the start.
Essential Tips
Aircraft remains are part of a war grave and memorial landscape. Leave every object exactly where it lies.
The old boundary fence is incomplete and may lead away from the safest ground. Use map, compass and GPX together.
If visiting the small bothy, leave it clean, carry out rubbish and never assume it will provide emergency shelter.
The upper mountain is pathless or faint in places. Waterproof boots and reliable navigation are essential.
Frequently Asked Questions
How long does it take to climb Arenig Fawr?
It usually takes 5 to 7 hours to complete the full route. The calculated time using Naismith's Rule is 3 hours 32 minutes, but you should allow extra for the remote terrain, navigation, and the long approach track.
Is there a clear path to the summit of Arenig Fawr?
No, there are few identifiable paths on Arenig Fawr. The approach track to the lake is clear, but beyond that the mountain is remote with only faint or nonexistent paths, so you'll need a map and compass.
What's the aircraft memorial on Arenig Fawr?
It commemorates American airmen killed when a B-17 bomber crashed on the mountain in 1943. The wreckage is part of a war grave—treat it with respect and leave everything undisturbed.