Cwm Hirnant by the Bwlch Hirnant track up Pen y Boncyn Trefeilw: route map, distance and time
644 m · Snowdonia
A hard mountain walk to the summit from Cwm Hirnant public track at SH952299.
The Cwm Hirnant by the Bwlch Hirnant track starts at about 344 m and gains 290 m over 3.2 km to 638 m on the track. The first kilometre climbs 118 m. The steepest kilometre is the one ending at 2 km, which climbs 129 m at an average of 13%, with a 500 m stretch from 0.7 km at about 22%. The final 0.2 km eases to the top. About 10% of the way is steeper than 1 in 5, so expect hands-on-knees going and a slow descent.
Cwm Hirnant by the Bwlch Hirnant track at a glance
| Distance | 3.2 km one way, to the top |
|---|---|
| Ascent | 300 m |
| Climb on the track | 290 m up, 0 m down on the way |
| Start and top of the track | 341 m to 638 m (summit 644 m) |
| Steepest 500 m | About 22%, from 0.7 km |
| Steeper than 1 in 5 | 10% of the way |
| Time up | 1h 10m by Naismith's rule |
| There and back | 1h 45m, down the same way |
| Grade | Hard |
| Start | Cwm Hirnant public track at SH952299 |
| Start grid reference | SH 952 299 |
| Summit grid reference | SH 962 283 |
| Parking | No checked car park for this start; find lawful parking nearby |
Cwm Hirnant by the Bwlch Hirnant track map
The track from the start (green) to the summit (blue), with a marker at each kilometre.
Height profile and getting to the start
Download the Cwm Hirnant by the Bwlch Hirnant track GPX
Ascent only: plan your way down. A planning track, not checked on the ground; it doesn't show safe scrambling moves. Track data © OpenStreetMap contributors (ODbL), heights from a terrain model.
Cwm Hirnant by the Bwlch Hirnant track kilometre by kilometre
Height, climb and average gradient for each kilometre of the track, with a grid reference at the end of each one to check your position on the map.
| At | Height | Climb | Gradient | Grid ref |
|---|---|---|---|---|
| 1 km | 462 m | +118 m | 12% | SH 956 290 |
| 2 km | 590 m | +129 m | 13% | SH 953 282 |
| 3 km | 637 m | +47 m | 5% | SH 960 282 |
| 3.2 km | 638 m | +1 m | 1% | SH 962 283 |
How long the Cwm Hirnant by the Bwlch Hirnant track takes
| Pace | To the top | There and back |
|---|---|---|
| Brisk 6 km/h, 8 min per 100 m up | 0h 55m | 1h 30m |
| Steady (Naismith) 5 km/h, 10 min per 100 m up | 1h 10m | 1h 45m |
| Relaxed 4 km/h, 12 min per 100 m up | 1h 25m | 2h 10m |
Times leave out stops. Coming down the same way, the table counts the ascent once; steep descents on rough ground can be as slow as the climb.
- Today: sunrise 07:04, sunset 16:51. Start by 14:06 to be down before dark, allowing 1h 45m for the walk and an hour for stops.
- Tomorrow: sunrise 07:05, sunset 16:49. Start by 14:04 to be down before dark, allowing 1h 45m for the walk and an hour for stops.
Pen y Boncyn Trefeilw summit weather for this route
There is no recent summit forecast cached for Pen y Boncyn Trefeilw right now. The main Pen y Boncyn Trefeilw page loads the live forecast when you open it. Open the live Pen y Boncyn Trefeilw forecast.
Before you go, also check: MWIS Snowdonia forecast · Met Office mountain forecast.
About Pen y Boncyn Trefeilw
More about Pen y Boncyn Trefeilw, with the live forecast.
Challenges that include Pen y Boncyn Trefeilw
More walks from Cwm Hirnant public track at SH952299
Routes in Peakify's guides that start within 500 m of this one, for another day from the same car park.
- Cwm Hirnant by the Bwlch Hirnant track up Stac Rhos
- Cwm Hirnant by the Bwlch Hirnant track up Foel Cedig
- Cwm Hirnant by the Bwlch Hirnant track up Y Groes Fagl
- Cwm Hirnant by the Bwlch Hirnant track up Foel Cwm-Sian Llwyd
Other routes up Pen y Boncyn Trefeilw
| Route | Distance | Ascent | Time up | Grade |
|---|---|---|---|---|
| Cwm Hirnant by the forest tracks | 4.2 km one way | 330 m | 1h 25m | Hard |
In an emergency
Call 999, ask for the police and then mountain rescue. Give your location (the start is at SH 952 299, the summit at SH 962 283), what happened and how many are in your group. If you have no signal for a call, a text to 999 works once you have registered your phone with emergencySMS: text "register" to 999 before you go.
Cwm Hirnant by the Bwlch Hirnant track: questions and answers
How far is the Cwm Hirnant by the Bwlch Hirnant track?
The Cwm Hirnant by the Bwlch Hirnant track is 3.2 km one way to the summit of Pen y Boncyn Trefeilw, with 300 m of ascent. There and back by the same way is about 6.4 km.
How long does the Cwm Hirnant by the Bwlch Hirnant track take?
About 1h 10m to the summit of Pen y Boncyn Trefeilw and 1h 45m there and back by Naismith's rule (5 km/h plus 10 minutes per 100 m of ascent), before stops. A relaxed group takes nearer 2h 10m for the round trip.
How steep is the Cwm Hirnant by the Bwlch Hirnant track?
The steepest 500 m averages about 22%, starting 0.7 km from the start, and 10% of the way is steeper than 1 in 5. The Cwm Hirnant by the Bwlch Hirnant track climbs 290 m in all on the track.
Where do you park for the Cwm Hirnant by the Bwlch Hirnant track?
The Cwm Hirnant by the Bwlch Hirnant track starts from Cwm Hirnant public track at SH952299. The grid reference is SH 952 299. No checked car park for this start; find lawful parking nearby
Is the Cwm Hirnant by the Bwlch Hirnant track suitable for beginners?
Not as a first mountain. Peakify grades it Hard: steep, rough ground where a slip matters. Build up on an easier route first.
What time should I start the Cwm Hirnant by the Bwlch Hirnant track today?
By 14:06 at the latest. Sunset on Pen y Boncyn Trefeilw today is 16:51, The Cwm Hirnant by the Bwlch Hirnant track takes about 1h 45m there and back, and that leaves an hour for stops. Start earlier in winter or if the forecast turns.
Is there a GPX for the Cwm Hirnant by the Bwlch Hirnant track?
Yes. Download it from this page. It is an ascent-only planning track from the start to the summit, plotted on OpenStreetMap paths and not checked on the ground.