Elidir Fawr and Marchlyn Circuit.

Elidir Fawr tends to elicit the memory in many either of the endless slog from Nant Peris, or of the scars of the Dinorwig quarries above Llanberis.  This is a route over the mountain’s quieter and arguably better side, though the mark of man is here as clear as elsewhere.

The far north peak of Carnedd y Filiast has the encroaching Penrhyn Quarries nearby, and the main summit of Elidir Fawr has a hydro power plant built inside it, hence the nick name of ‘Electric Mountain’.


Distance, Ascent and Time 10.5km, 960m ascent, 4 hours

OS Map Required Explorer 017BMC MapLandranger 115

Difficulties Routefinding in mist and descent described is steep in places.

Start / End  Deiniolen

Facilities Roadside parking only.

Public Transport Fequent bus service to Deiniolen from Caernarfon or Bangor.

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The Route It turned out to be a dry morning, so there’s just one thing for it. Hit the hills. I decided to minimise effort (lazy) i would climb Elidir Fawr from below the Reservoir, meaning I could start the walk at about 370m, and my knees would be grateful for that.  The walk starts at Grid Reference 596631, at a carpark at the top of Deiniolen. There appears to be some sort of camp here too, with caravans and old buses taking the car park over, so you’ll probably need to park lower down. Or better still, use the bus to get here.

Its an easy stroll up the access road up to the reservoir, before you turn off the road at the fork at 615624, which is another tarmac road leading to real hill a 100m or so distant. This is the start of the day, where a relatively steep, and indistinct in places, path leads up to the bwlch below Carnedd y Filiast. At this point, i was nearly blown off my feet, so had to shelter for a few minutes, have a brew and consider my options.

Obviously, I couldn’t turn back, so I kept on, against the wind, and falling over at regular intervals until I found a sheltered spot, so I rested there for a few mins, before the final stretch for the summit. And then, the wind slowed.

Anyway, no view, so I continued to Mynydd Perfedd where the summit shelter was a good point to have a hot flask of soup.

From here it was decision time. Over Elidir Fawr and back to Deiniolen, or down via Cwm Dudodyn to Nant Peris. However, when I reached the start of the Nant Peris path, it was hoplessly steep and eroded, so the summit of Elidir Fawr was to be tackled, with hope that the daylight would be sufficient.

Marvellous day, up to now, when I decided to descend the northern slopes of Elidir Fawr, straight down to the track. This turned out to be a nasty descent over loose, slippery, bouldery scree before relenting to merely loose, slippery scree. A better route  is to continue further along the ridge and then descend a path to Elidir Fach. Follow the ridge then down to the reservoir track you started on and back to the start and is described as an ascent in this route.

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