Cwm Mynach via Diffwys up Diffwys West Top: route map, distance and time
643 m · Snowdonia
A hard mountain walk to the summit from Dolmelynllyn car park, Ganllwyd.
Cwm Mynach via Diffwys starts at about 54 m and gains 1,152 m over 14.6 km to 637 m on the track. The first kilometre climbs 41 m. The steepest kilometre is the one ending at 12 km, which climbs 209 m at an average of 21%, with a 500 m stretch from 11.8 km at about 34%. The final 0.6 km eases to the top. About 12% of the way is steeper than 1 in 5, so expect hands-on-knees going and a slow descent.
Cwm Mynach via Diffwys at a glance
| Distance | 14.6 km one way, to the top |
|---|---|
| Climb on the track | 1,152 m up, 569 m down on the way |
| Start and top of the track | 50 m to 731 m (summit 643 m) |
| Steepest 500 m | About 34%, from 11.8 km |
| Steeper than 1 in 5 | 12% of the way |
| Grade | Hard |
| Start | Dolmelynllyn car park, Ganllwyd, LL40 2TF |
| Start grid reference | SH 726 243 |
| Summit grid reference | SH 648 229 |
| Parking | Dolmelynllyn car park, Ganllwyd (SH727243) |
Cwm Mynach via Diffwys map
The track from the start (green) to the summit (blue), with a marker at each kilometre.
Height profile and getting to the start
Near the start
From OpenStreetMap, within 2 km. Check opening times before you rely on them.
Download the Cwm Mynach via Diffwys 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 Mynach via Diffwys 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 | 95 m | +41 m | 4% | SH 724 241 |
| 2 km | 240 m | +145 m | 14% | SH 719 234 |
| 3 km | 427 m | +187 m | 19% | SH 714 228 |
| 4 km | 586 m | +159 m | 16% | SH 705 230 |
| 5 km | 511 m | -74 m | -7% | SH 698 230 |
| 6 km | 417 m | -94 m | -9% | SH 693 222 |
| 7 km | 299 m | -118 m | -12% | SH 690 217 |
| 8 km | 190 m | -109 m | -11% | SH 686 218 |
| 9 km | 225 m | +35 m | 4% | SH 688 227 |
| 10 km | 268 m | +42 m | 4% | SH 681 228 |
| 11 km | 336 m | +68 m | 7% | SH 674 233 |
| 12 km | 545 m | +209 m | 21% steep | SH 667 235 |
| 13 km | 731 m | +186 m | 19% | SH 661 235 |
| 14 km | 636 m | -95 m | -10% | SH 654 229 |
| 14.6 km | 637 m | +2 m | 0% | SH 648 228 |
How long Cwm Mynach via Diffwys takes
| Pace | To the top | There and back |
|---|---|---|
| Brisk 6 km/h, 8 min per 100 m up | 4h 0m | 6h 25m |
| Steady (Naismith) 5 km/h, 10 min per 100 m up | 4h 50m | 7h 45m |
| Relaxed 4 km/h, 12 min per 100 m up | 5h 55m | 9h 35m |
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.
Diffwys West Top summit weather for this route
There is no recent summit forecast cached for Diffwys West Top right now. The main Diffwys West Top page loads the live forecast when you open it. Open the live Diffwys West Top forecast.
Before you go, also check: MWIS Snowdonia forecast · Met Office mountain forecast.
About Diffwys West Top
More about Diffwys West Top, with the live forecast.
Challenges that include Diffwys West Top
More walks from Dolmelynllyn car park, Ganllwyd
Routes in Peakify's guides that start within 500 m of this one, for another day from the same car park.
- Ganllwyd and Rhaeadr Ddu forest paths up Y Garn
- Cwm Mynach and eastern ridge up Crib-y-rhiw
Other routes up Diffwys West Top
| Route | Distance | Ascent | Time up | Grade |
|---|---|---|---|---|
| Talybont via the southern ridge | 7.0 km one way | 480 m | 2h 10m | Hard |
In an emergency
Call 999, ask for the police and then mountain rescue. Give your location (the start is at SH 726 243, the summit at SH 648 229), 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 Mynach via Diffwys: questions and answers
How far is Cwm Mynach via Diffwys?
Cwm Mynach via Diffwys is 14.6 km one way to the summit of Diffwys West Top. There and back by the same way is about 29.2 km.
How steep is Cwm Mynach via Diffwys?
The steepest 500 m averages about 34%, starting 11.8 km from the start, and 12% of the way is steeper than 1 in 5. Cwm Mynach via Diffwys climbs 1,152 m in all on the track.
Where do you park for Cwm Mynach via Diffwys?
Cwm Mynach via Diffwys starts from Dolmelynllyn car park, Ganllwyd (postcode LL40 2TF). The grid reference is SH 726 243. Dolmelynllyn car park, Ganllwyd (SH727243)
Is Cwm Mynach via Diffwys 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.
Is there a GPX for Cwm Mynach via Diffwys?
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.