On the summit of Arenig Fawr, a memorial marks the place where an American B-17 Flying Fortress bomber crashed on 4 August 1943. All eight crew died.
The walk to it is 7¼ miles there and back, with 530 m of climbing. It starts at a layby above Llyn Celyn and passes Llyn Arenig Fawr, a lake, on foot.
Where the walk starts
The walk starts on the minor road near the hamlet of Arenig, at a layby that overlooks Llyn Celyn. Mud and Routes, a UK walking-route publisher, gives the grid reference as SH845 395.
Christopher Somerville, walking correspondent of The Times newspaper, says the road to Arenig is signed off the A4212 between Trawsfynydd and Bala.
The parking space is two-thirds of a mile past the hamlet, on the left, opposite a gate signed “Farmland”.
The postcode LL23 7PA brings you close, but it is only approximate. If the layby is full, Mud and Routes names two other places:
- the old quarry, at SH829 391
- a small space at the junction with the A4212, at SH816 393
The layby is the closest start to the track, and the quarry and the junction are the fallbacks.
The climb from the lake to the summit
The route is an out-and-back walk, so you follow one line up and come down the same way. In order:
- Go through the gate opposite the parking space and follow the track. It starts steeply, then levels out.
- After about 1½ miles you reach Llyn Arenig Fawr, below the cliffs of Simdde Ddu. A small bothy (a basic shelter) stands by the lake.
- Cross the ladder stile by the bothy and follow the path. The gradient is gentle at first.
- Climb a rocky, steep slope from 400 m at the bothy to 600 m at a fence. Maps name this slope Y Castell.
- Above the fence, follow the path to the summit. It is rocky, and a few cairns (piles of stones) mark it.
Near the summit, Somerville advises you to aim for a prominent post above you, then the trig pillar. A trig pillar is a concrete survey marker.
The rocky steps on Y Castell can be avoided to one side or the other, according to Mud and Routes. Higher up, it describes boggy sections and a path that sometimes vanishes.
What is on the summit
The summit stands at 854 m (2,802 ft), the height both Somerville and the walk-route site go4awalk give. It has a stone-walled shelter, the trig pillar and the memorial.
The aircraft is listed by Coflein, the online record of Welsh historic sites. The Royal Commission on the Ancient and Historical Monuments of Wales keeps it. These are its facts:
- Aircraft: Boeing B-17 Fortress 42-3124
- Unit: the 303rd Bomb Group, part of the US 8th Air Force
- Take-off: 23:54 on 3 August 1943, on a routine flight across country
- Crash: 01:00 on 4 August 1943
- Recorded cause: crashed into high ground
Coflein says the aircraft struck about 50 ft below the summit. It then continued to the peak, where it burst into flames.
All eight crew were killed.
The memorial has changed over time. The 303rd Bomb Group Association, the veterans’ and historians’ group of the crew’s unit, says a plaque went up in 1945.
A bronze replacement of the same size and wording has been in place since 31 August 2019.
Coflein recorded a metal plaque on the summit cairn in March 2025.
It also recorded a slate-framed photograph of the crew.
The remains of the aircraft are a Protected Place. Under the Protection of Military Remains Act 1986, it is an offence to interfere with the wreckage without a licence. Leave anything you find where it lies.
How long it takes and how hard it is
No source gives a time for the out-and-back walk. Somerville gives the distance and the climb, and calls it a strenuous mountain expedition for fit, sure-footed walkers.
Mud and Routes lists a longer circuit that adds Moel Llyfnant: 17.1 km, 792 m of climbing and 6 hours.
That is a different and longer day, so do not use it as a time for this one.
Mud and Routes lists the hazards as navigation and boggy sections, and the bothy as the only facility. The walk-route site go4awalk lists the map as OS Explorer OL18.
Carry a paper map, and check the mountain forecast before you set off.
Somerville says you need a clear day on the tops.
Welsh Country Magazine, a Wales lifestyle magazine, writes that Arenig Fawr is unlikely to ever be busy.
Somerville places it at the eastern edge of the National Park, some way from the better-known peaks.
Other walks in Eryri to plan after this one include Aran Fawddwy and Rhinog Fawr, or the Precipice Walk.
The view west and the way down
From the trig pillar, Somerville names Snowdon to the north-west and Cadair Idris to the south-west. To the east he lists the Clwydian Hills and the Berwyns.
Mud and Routes says the views across all of Snowdonia are superb if the weather is clear, though a little distant.
If cloud covers the top, Mud and Routes says to get the compass out.
We compile and explain public route and safety information. We guide nobody and sell nothing on the hill.
Go back by the same route.
The cairned rocky path leads down to the fence, then comes the steep slope of Y Castell, the bothy at the lake and the track to the layby above Llyn Celyn.
