Llynnau Cwm Silyn approach up Craig Cwm Silyn: route map, distance and time
734 m · Snowdonia
Craig Cwm Silyn is the 734 m high point of the Nantlle Ridge in Snowdonia, with the Great Slab climbing crag and two lakes in the cwm below.
A hard mountain walk to the summit from Llyn Cwmdulyn road-end car park, Nebo.
Llynnau Cwm Silyn approach starts at about 233 m and gains 658 m over 7.0 km to 705 m on the track. The first 5 km are the easy part, averaging 4%. The steepest kilometre is the one ending at 6 km, which climbs 207 m at an average of 21%, with a 500 m stretch from 5.1 km at about 29%. The final kilometre eases to the top. About 13% of the way is steeper than 1 in 5, so expect hands-on-knees going and a slow descent.
Llynnau Cwm Silyn approach at a glance
| Distance | 7.0 km one way, to the top |
|---|---|
| Ascent | 690 m |
| Climb on the track | 658 m up, 182 m down on the way |
| Start and top of the track | 233 m to 717 m (summit 734 m) |
| Steepest 500 m | About 29%, from 5.1 km |
| Steeper than 1 in 5 | 13% of the way |
| Time up | 2h 35m by Naismith's rule |
| There and back | 3h 55m, down the same way |
| Grade | Hard |
| Start | Llyn Cwmdulyn road-end car park, Nebo |
| Start grid reference | SH 488 498 |
| Summit grid reference | SH 525 502 |
| Parking | Llyn Cwmdulyn road-end car park, Nebo |
Llynnau Cwm Silyn approach 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 Llynnau Cwm Silyn approach 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.
Llynnau Cwm Silyn approach 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 | 325 m | +92 m | 9% | SH 497 498 |
| 2 km | 433 m | +108 m | 11% | SH 503 499 |
| 3 km | 287 m | -146 m | -15% | SH 500 508 |
| 4 km | 337 m | +50 m | 5% | SH 505 511 |
| 5 km | 444 m | +107 m | 11% | SH 509 504 |
| 6 km | 651 m | +207 m | 21% steep | SH 516 499 |
| 7 km | 705 m | +53 m | 6% | SH 525 502 |
How long Llynnau Cwm Silyn approach takes
| Pace | To the top | There and back |
|---|---|---|
| Brisk 6 km/h, 8 min per 100 m up | 2h 5m | 3h 15m |
| Steady (Naismith) 5 km/h, 10 min per 100 m up | 2h 35m | 3h 55m |
| Relaxed 4 km/h, 12 min per 100 m up | 3h 10m | 4h 55m |
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 07:07, sunset 16:53. Start by 11:58 to be down before dark, allowing 3h 55m for the walk and an hour for stops.
- Tomorrow: sunrise 07:09, sunset 16:51. Start by 11:56 to be down before dark, allowing 3h 55m for the walk and an hour for stops.
Craig Cwm Silyn summit weather for this route
There is no recent summit forecast cached for Craig Cwm Silyn right now. The main Craig Cwm Silyn page loads the live forecast when you open it. Open the live Craig Cwm Silyn forecast.
Before you go, also check: MWIS Snowdonia forecast · Met Office mountain forecast.
About Craig Cwm Silyn
Craig Cwm Silyn is the 734 m high point of the Nantlle Ridge in Snowdonia, with the Great Slab climbing crag and two lakes in the cwm below. More about Craig Cwm Silyn, with the live forecast.
On the lists: Hewitt, Nuttall, Marilyn.
Extend the walk: tops near the summit
- Mynydd Tal-y-mignedd (653 m), 1.5 km north-east
- Garnedd-goch (700 m), 1.6 km south-west
- Trum y Ddysgl (710 m), 2.4 km north-east
- Mynydd Drws-y-coed (695 m), 2.8 km north-east
Challenges that include Craig Cwm Silyn
More walks from Llyn Cwmdulyn road-end car park, Nebo
Routes in Peakify's guides that start within 500 m of this one, for another day from the same car park.
- Nantlle Ridge from Nebo up Garnedd-goch
- Nantlle Ridge from Nebo up Mynydd Graig Goch
Other routes up Craig Cwm Silyn
| Route | Distance | Ascent | Time up | Grade |
|---|---|---|---|---|
| Nantlle Ridge from Rhyd Ddu | 5.4 km one way | — | — | Hard |
| Nantlle Ridge from Nebo | 5.8 km one way | 600 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 488 498, the summit at SH 525 502), 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.
Llynnau Cwm Silyn approach: questions and answers
How far is Llynnau Cwm Silyn approach?
Llynnau Cwm Silyn approach is 7.0 km one way to the summit of Craig Cwm Silyn, with 690 m of ascent. There and back by the same way is about 14.0 km.
How long does Llynnau Cwm Silyn approach take?
About 2h 35m to the summit of Craig Cwm Silyn and 3h 55m 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 4h 55m for the round trip.
How steep is Llynnau Cwm Silyn approach?
The steepest 500 m averages about 29%, starting 5.1 km from the start, and 13% of the way is steeper than 1 in 5. Llynnau Cwm Silyn approach climbs 658 m in all on the track.
Where do you park for Llynnau Cwm Silyn approach?
Llynnau Cwm Silyn approach starts from Llyn Cwmdulyn road-end car park, Nebo. The grid reference is SH 488 498. Llyn Cwmdulyn road-end car park, Nebo
Is Llynnau Cwm Silyn approach 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 Llynnau Cwm Silyn approach today?
By 11:58 at the latest. Sunset on Craig Cwm Silyn today is 16:53, Llynnau Cwm Silyn approach takes about 3h 55m there and back, and that leaves an hour for stops. Start earlier in winter or if the forecast turns.
Is there a GPX for Llynnau Cwm Silyn approach?
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.