logo Walking Britain

Snowdonia Walk
Elidir Fawr, Mynydd Perfedd & Marchlyn Mawr reservoir

Nat Park - Snowdonia - Glyders Tryfan

County/Area - Gwynedd

Author - Alwyn Williams

Length - 6.0 miles / 9.8 km

Ascent - 2400 feet / 727 metres

Time - 5 hours 20 minutes

Grade - moderate

Start - OS grid reference SH596631
Lat 53.146486 // Long -4.100712
Postcode LL55 3NA (approx. location only)

Walk Route Description

Photo from the walk - Elidir Fawr, Mynydd Perfedd & Marchlyn Mawr reservoir Photo from the walk - Elidir Fawr, Mynydd Perfedd & Marchlyn Mawr reservoir Photo from the walk - Elidir Fawr, Mynydd Perfedd & Marchlyn Mawr reservoir
Click thumbnails for larger images.

This Snowdonia walk takes in three mountains, namely Carnedd y Filiast, Mynydd Perfedd and Elidir Fawr. The route starts at the end of the access road to the Marchlyn Mawr reservoir from Deiniolen (Grid ref. SH604627). The reservoir feeds the Dinorwig Hydro-Electric Power Station which is built inside Elidir Fawr.

Head up through the gate and follow the access road uphill passing the old disused quarry on your right. Continuing on you will pass the Marchlyn Bach lake on your right. Follow the road until it forks (Grid ref. SH615624) and take the left fork.

After approx 100m the start of the path can be seen forking right up to a wooden stile. Continue on over the stile and follow the faint path up towards the shoulder. From the shoulder you can go left to an unnamed summit which looks down towards the Bethesda Quarry or continue right towards Carnedd Y Filiast. From the shoulder continue up the path over ground which becomes steadily rockier and eventually crossing large boulders to the summit of Carnedd Y Ffiliast (Grid ref. SH620627). There are spectacular views now of the Ogwen Valley, the Carneddau , Tryfan, the Glyders and Snowdon.

From the summit of Carnedd Y Ffiliast continue in a south easterly direction towards a wall with a stile, keeping the cliffs down to Ogwen on your left. Once over the wall follow the faint path towards the flat summit of Mynydd Perfedd. From here you see Elidir Fawr from its most dramatic side with large cliffs to the side of the summit and a very steep looking approach towards the summit itself.

From the summit shelter of Mynydd Perfedd head west towards the stile over the fence. Once you have crossed the stile take the right fork on the path towards the ridge (Grid ref. SH619615) which divides the summits on Mynydd Perfedd and Elidir Fawr. Follow the path across the rocks of Bwlch Marchlyn towards the rocky summit of Elidir Fawr whilst keeping the Marchlyn Mawr reservoir below you and to the right.

From the summit shelter of Elidir Fawr continue along the summit ridge for approx 200m and descend down the faint path in the scree towards the summit of Elidir Fach (Grid ref. SH603613). Once on the summit of Elidir Fach walk in a northerly direction towards the Marchlyn Bach reservoir. Keep the cliffs and the steep drop to your right whilst descending along the path until you reach a wall. Follow the wall down towards the Marchlyn Bach reservoir then cross the gate to reach the access road to Marchlyn Mawr reservoir. Follow the road back down to the start of the route.

Please maintain social distancing - keep at least 2 metres away from other walkers.

Maps Ordnance Survey Logo Anquet Maps Logo

Ordnance Survey Explorer OL17Sheet Map1:25kBUY
Anquet OS Explorer OL17Digital Map1:25kBUY
Ordnance Survey Landranger 115Sheet Map1:50kBUY
Anquet OS Landranger 115Digital Map1:50kBUY

It is recommended you take a map. The preferred scale is 1:25k.

GPS files - right click or option-click the button and choose "Save As..." to download this file.


Recommended Books & eBooks

The Wales Coast Path

The Wales Coast PathA single guidebook to walking the whole Wales Coast Path - 1400km (870 miles) the length of Wales from Chester to Chepstow, including Anglesey, described in 57 stages. The route passes through the Snowdonia and Pembrokeshire National Parks and many AONBs and can be linked with the Offa's Dyke Path for a complete circuit of Wales.
More information

Snowdonia: 30 Low-level and easy walks - South

Snowdonia: 30 Low-level and easy walks - SouthGuidebook describing 30 walks in Snowdonia, Wales. Routes are mostly low level and on clear paths and showcase the region's beautiful scenery and rich history and culture. Part of a 2-volume set, this southern volume includes Trawsfynydd, Bala, Dolgellau, Machynlleth, the Harlech Coast and the valleys of the Mawddach and Dyfi.
More information

The National Trails

The National TrailsThis inspirational guidebook looks at each of the UK's 19 National Trails, with information that allows ease of comparison and contrast, inspiring you to find out more and to take up a long-distance challenge. Some Trails are short and easy, others much longer, many have strong themes - they may follow a coastline, or traverse ranges of hills.
More information

Social Media

Follow Walking Britain for the latest news.

Facebook Twitter

Walking - Covid 19 update

Regular updates on how Covid 19 will impact on walking in the UK More info.

Mountain Weather

Stay safe on the mountains with detailed weather forecasts - for iOS devices or for Android devices.

Digital Mapping Guide

Digital Mapping Guide - a simple guide of how to start using digital mapping. Includes advice and useful links.