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Walk up Elidir Fawr and Y Garn from Marchlyn / Deiniolen

By Dave Roberts   

on January 16, 2022    No ratings yet.

Walk up Elidir Fawr and Y Garn from Marchlyn / Deiniolen

Further Details

Route Summary:

A circular route from Deiniolen that takes in Elidir Fawr, Y Garn and Carnedd y Filiast.

This walk includes the 4 Washis of Y Garn (Glyderau), Elidir Fawr, Foel-goch, Carnedd y Filiast (Glyderau)

This walk includes the 4 Hewitts of Y Garn (Glyderau), Elidir Fawr, Foel-goch, Carnedd y Filiast (Glyderau)

This walk includes the 6 Nuttalls of Y Garn (Glyderau), Elidir Fawr, Foel-goch, Carnedd y Filiast (Glyderau), Mynydd Perfedd, Carnedd y Filiast North Top (Y Fronllwyd)

Route Start Location: Roadhead Marchlyn

15.2km 1100 m 6 hours

Calculate the time using Naismith’s Rule and factor in your own pace.

Activivity Type: Hard Walk

Summits and Places on this Route


Convenience shop in Deinolen and the Lodge Dinorwig cafe in Dinorwig.


Steep scree up Glyder Fawr, Route finding in mist. Down Scramble of Y Gribin Ridge has a couple of steep sections – read our Glyder Fach via Y Gribin for more information on this scramble.

Remember that we cannot outline every single hazard on a walk – it’s up to you to be safe and competent. Read up on Mountain Safety , Navigation and what equipment you’ll need.

Parking :

There’s room for a number of cars on the roadside at the start of this walk.

Public Transport:

Sherpa Buses and local buses from Caernarfon and Bangor.

Traveline for UK Public Transport

Recommended Maps


Walk up Elidir Fawr and Y Garn from Marchlyn / Deiniolen Ordnance Survey Map and GPX File Download

Download file for GPS

Walk up Elidir Fawr and Y Garn from Marchlyn / Deiniolen

The walk up Y Garn is one of the more popular walks from Ogwen in Snowdonia, but provides a longer, quieter, and arguably more satisfying walk from the unfashionable Dinorwig/Deiniolen end of the mountain range. This walk also includes the mountain of Elidir Fawr, which is usually a slog from all directions, some high grassy ridge walking, and a final descent over two or three further summits, depending how keen of a bagger you are! Those looking for a shorter excursion can walk just the Elidir Fawr – Filiast circuit around Marchlyn Mawr and exclude Y Garn.

Walk up Elidir Fawr and Y Garn from Marchlyn / Deiniolen Route Description

The walk starts where the public road to the Marchlyn Reservoir ends at SH593 631, where there’s usually room to park a car or two. You can also start from the village of Deinolen, or Dinorwig by following the minor roads to the start of the walk. There is a regular (by current day standards, make of that what you will) bus service to these villages from Caernarfon, Bangor and Llanberis (which you can reach on foot from Dinorwig in around 30 minutes, making a circuit less dependent on catching a bus back to the start)

1 – Walk up the road to the gate that marks the end of the public road and the start of the private road up to Marchllyn Fawr. Pass through the kissing gate to the left and continue on the road for about 1km where soon after passing a quarry to your right you’ll reach a junction.

2 – At the junction, head towards the gate between the roads and cross the stile. Head right where a faint path rises initially along with the wall. The small reservoir of Marchlyn Bach will start to come into view to your left. The path then curves left along the blunt grassy ridge high above the lake, with the climb being a steep slog in places. You need to be aiming for the skyline, preferably veering to your right as the minor summit of Elidir Fach is the day’s first goal. The grassy slope is a little tedious, but once views open towards Llyn Padarn and Marchlyn Mawr, it becomes much more pleasant. Neither is it a long slog like its counterpart from Nant Peris, The climb eventually relents, the grass giving way to stonier and more level ground that leads to the very minor summit of Elidir Fach

3 – Continue on the plateau for around 0.5km, depending on your ascent route, to reach Elidir Fach. Be aware that the path is faint, and the going can be tricky in mist and will probably necessitate taking a compass bearing.

4 – What Elidir Fach lacks in status, it makes up for with a summit shelter that provides the only respite on this plateau, as well as extensive views. To one side you have Snowdon and Crib Goch and across Crib Nantlle, Ynys Mon and on to the Carneddau. Behind you lies the the scree covered lump of Elidir Fawr. If it’s clear, you can make out the path that crosses the scree at an angle away from you. If it’s misty, then there’s a fence that can be followed to the summit ridge. Even if it’s clear, the closer you get to the path, the more difficult it is to spot. Once on it, then it’s abundantly clear. A short sharp climb brings you up to the summit ridge.

5 – The approach to Elidir Fawr along the summit ridge is bouldery and a welcome change from steep grass and scree. It’s a wide ridge, but nevertheless provides some excitement to the approach that’s helped along with the breath-taking views across the Carneddau, Glyderau and Yr Wyddfa. The sunken summit shelter provides welcome respite on what can be a ridge exposed to the elements.

6 – From the summit shelter of Elidir Fawr, Continue over the summit and follow the path roughly eastwards. It contours the top of Cwm Dudodyn, and the base of Mynydd Perfedd which you’ll be returning over later. You quickly arrive at the base of Y Foel Goch, the ascent ahead up the steep scree being clearly apparent. The slog isn’t as bad as it first looks, and you find yourself almost on top before you start getting fed up with it. It steepens as you near the top, but then abruptly flattens off into a large grassy plateau. The summit itself is a small area with sheer drops on most sides, so take care in mist. Follow the fence that crosses the summit (right, obviously not left) and easy walking takes you over grass to the start of the next ascent, Y Garn.

7 – Yet another scree path takes you up this fine mountain, providing around 200m of climb before relenting just below the summit as it joins the Garn NE Ridge from Ogwen for the final few steps to the top. Of course, the views continue to be breath-taking, with Tryfan and Y Glyderau now taking centre stage. The complete traverse of the Glyderau, across these summits is one of the finest walks in the country, but that will have to wait for another day .

8 – Retrace your steps back down Y Garn, and rather than continue to the plateau towards Foel-goch, take the more obvious path left that contours around the base of Foel-goch to the start of the earlier climb up Foel-goch. Continue for 300m as you approach Mynydd Perfedd, and ascend it directly as soon as you reach it.

9 – Moel Perfedd does involve a grassy slog, which is quite unwelcome at this late stage of the walk. Thankfully, once completed there’s a welcome summit shelter and an excuse to finish off whatever’s left in your flask while taking in the view towards Carnedd Dafydd and back along the ridge towards Y Garn and of Elidir Fawr’s Craig Cwrwgl that drop into Marchlyn Mawr.

10 – Continue along the wide grassy ridge towards the final summit of Carnedd y Filiast. You’ll cross the stone wall at the stile and you’re nearly at the summit. The way ahead is not obvious, with the path faint and the terrain unsympathetically stony. There’s also a number of routes you can take, including directly over the summit. We prefer to head roughly NE from the summit on more grassy terrain which then heads west to a gap (you can spot the ring contour on the map) which brings you to the descent path.

11 – Continue down the scree path (yes, there’s a lot of scree on this walk!) – keeping left rather than heading towards steeper scree towards the north eastern section of the slope. In clear weather you can see the ground relent below, which makes navigation a bit easier.

From the grassy area, head west (left) downhill along what’s becoming a clearer path over the years. This brings you down to the reservoir road.

Alternatively – you can first walk north towards spot height 721 (Carnedd y Filiast North Top (Y Fronllwyd)) for a final summit of the day. If you’ve got the time, then why not.

Dave Roberts founded Walk Eryri in 2004, with the aim of providing routes that are off the beaten track. Walk Eryri is now part of Mud and Routes which continues to provide more off beat routes and walks in Snowdonia and beyond. Dave has been exploring the hills of Eryri for over thirty years, and is a qualified Mountain Leader. Dave also established Walk up Snowdon, Walk up Scafell Pike and Walk up Ben Nevis just to mention a few.
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