Cwmorthin and Rhosydd from Tanygrisiau up Moelwyn Mawr: route map, distance and time
770 m · Snowdonia
Moelwyn Mawr is a 770 m Hewitt and Marilyn above Blaenau Ffestiniog and Croesor, the highest of the Moelwynion, ringed by old slate workings.
A hard mountain walk to the summit from Cwmorthin car park, Tanygrisiau.
Cwmorthin and Rhosydd from Tanygrisiau starts at about 259 m and gains 491 m over 4.8 km to 736 m on the track. The first 3 km are the easy part, averaging 7%. The steepest kilometre is the one ending at 4.8 km, which climbs 144 m at an average of 19%, with a 500 m stretch from 4.2 km at about 23%. That last pull ends at the summit. About 23% of the way is steeper than 1 in 5, so expect hands-on-knees going and a slow descent.
Cwmorthin and Rhosydd from Tanygrisiau at a glance
| Distance | 4.8 km one way, to the top |
|---|---|
| Ascent | 540 m |
| Climb on the track | 491 m up, 10 m down on the way |
| Start and top of the track | 258 m to 740 m (summit 770 m) |
| Steepest 500 m | About 23%, from 4.2 km |
| Steeper than 1 in 5 | 23% of the way |
| Time up | 1h 50m by Naismith's rule |
| There and back | 2h 50m, down the same way |
| Grade | Hard |
| Start | Cwmorthin car park, Tanygrisiau, LL41 3ST |
| Start grid reference | SH 683 454 |
| Summit grid reference | SH 658 448 |
| Parking | Cwmorthin car park, Tanygrisiau (SH68304542); the postcode is approximate |
Cwmorthin and Rhosydd from Tanygrisiau 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
- King's Head1.2 km
- Clwb y Ddraig Goch1.6 km
- Lakeside Cafe0.5 km
- Y Pafiliwn1.6 km
- Pethau Blasus1.9 km
- Public toilets2.0 km
From OpenStreetMap, within 2 km. Check opening times before you rely on them.
Download the Cwmorthin and Rhosydd from Tanygrisiau 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.
Cwmorthin and Rhosydd from Tanygrisiau 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 | 323 m | +64 m | 6% | SH 677 461 |
| 2 km | 360 m | +37 m | 4% | SH 669 466 |
| 3 km | 459 m | +99 m | 10% | SH 661 462 |
| 4 km | 592 m | +133 m | 13% | SH 661 453 |
| 4.8 km | 736 m | +144 m | 19% | SH 658 448 |
How long Cwmorthin and Rhosydd from Tanygrisiau takes
| Pace | To the top | There and back |
|---|---|---|
| Brisk 6 km/h, 8 min per 100 m up | 1h 30m | 2h 20m |
| Steady (Naismith) 5 km/h, 10 min per 100 m up | 1h 50m | 2h 50m |
| Relaxed 4 km/h, 12 min per 100 m up | 2h 15m | 3h 30m |
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 07:49, sunset 18:12. Start by 14:22 to be down before dark, allowing 2h 50m for the walk and an hour for stops.
- Tomorrow: sunrise 07:51, sunset 18:10. Start by 14:20 to be down before dark, allowing 2h 50m for the walk and an hour for stops.
Moelwyn Mawr summit weather for this route
There is no recent summit forecast cached for Moelwyn Mawr right now. The main Moelwyn Mawr page loads the live forecast when you open it. Open the live Moelwyn Mawr forecast.
Before you go, also check: MWIS Snowdonia forecast · Met Office mountain forecast.
About Moelwyn Mawr
Moelwyn Mawr is a 770 m Hewitt and Marilyn above Blaenau Ffestiniog and Croesor, the highest of the Moelwynion, ringed by old slate workings. More about Moelwyn Mawr, with the live forecast.
On the lists: Hewitt, Nuttall, Marilyn.
Extend the walk: tops near the summit
- Craigysgafn (690 m), 0.6 km south
- Moelwyn Bach (712 m), 1.1 km south
- Cnicht (691 m), 2.2 km north-west
- Cnicht North Top (690 m), 2.2 km north-west
Challenges that include Moelwyn Mawr
More walks from Cwmorthin car park, Tanygrisiau
Routes in Peakify's guides that start within 500 m of this one, for another day from the same car park.
- Cwmorthin, Rhosydd and the north ridge up Cnicht
- Llyn Stwlan and Bwlch Stwlan up Moelwyn Bach
- Cwmorthin via Moelwyn Mawr and Craigysgafn up Moelwyn Bach
- Tanygrisiau via Cwmorthin and Rhosydd up Cnicht North Top
- Tanygrisiau and Cwmorthin paths up Craigysgafn
- Tanygrisiau and Cwmorthin paths up Moel-yr-hydd
- Tanygrisiau via Cwmorthin and Rhosydd up Moel Druman
- Tanygrisiau via Cwmorthin and Rhosydd up Ysgafell Wen
- Tanygrisiau via Cwmorthin and Rhosydd up Ysgafell Wen North Top
- Tanygrisiau via Cwmorthin and Rhosydd up Ysgafell Wen Far North Top
Other routes up Moelwyn Mawr
| Route | Distance | Ascent | Time up | Grade |
|---|---|---|---|---|
| From Croesor by the north-west ridge | 3.7 km one way | 620 m | 1h 45m | Moderate |
| From Tanygrisiau via Craigysgafn | 4.4 km one way | 570 m | 1h 50m | Moderate |
| Croesor via Moelwyn Bach and Craigysgafn | 5.7 km one way | 730 m | 2h 20m | Hard |
In an emergency
Call 999, ask for the police and then mountain rescue. Give your location (the start is at SH 683 454, the summit at SH 658 448), 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.
Cwmorthin and Rhosydd from Tanygrisiau: questions and answers
How far is Cwmorthin and Rhosydd from Tanygrisiau?
Cwmorthin and Rhosydd from Tanygrisiau is 4.8 km one way to the summit of Moelwyn Mawr, with 540 m of ascent. There and back by the same way is about 9.6 km.
How long does Cwmorthin and Rhosydd from Tanygrisiau take?
About 1h 50m to the summit of Moelwyn Mawr and 2h 50m 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 3h 30m for the round trip.
How steep is Cwmorthin and Rhosydd from Tanygrisiau?
The steepest 500 m averages about 23%, starting 4.2 km from the start, and 23% of the way is steeper than 1 in 5. Cwmorthin and Rhosydd from Tanygrisiau climbs 491 m in all on the track.
Where do you park for Cwmorthin and Rhosydd from Tanygrisiau?
Cwmorthin and Rhosydd from Tanygrisiau starts from Cwmorthin car park, Tanygrisiau (postcode LL41 3ST). The grid reference is SH 683 454. Cwmorthin car park, Tanygrisiau (SH68304542); the postcode is approximate
Is Cwmorthin and Rhosydd from Tanygrisiau 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, such as the From Croesor by the north-west ridge.
What time should I start Cwmorthin and Rhosydd from Tanygrisiau today?
By 14:22 at the latest. Sunset on Moelwyn Mawr today is 18:12, Cwmorthin and Rhosydd from Tanygrisiau takes about 2h 50m there and back, and that leaves an hour for stops. Start earlier in winter or if the forecast turns.
Is there a GPX for Cwmorthin and Rhosydd from Tanygrisiau?
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.