If one makes the effort to pull themselves away from Cwm Idwal and its famous winter test pieces and up into the less accessible hanging valley of Cwm Cenifion, one will find themselves in the midst of a satisfying array of quality winter routes. Hidden Gully, a 100 metre Grade II, is one of the Cwm’s finest and despite its name, isn’t all that hard to find. It can be found on the far right hand side of the Cwm tucked away just behind the obvious mass of crags known as Clogwyn Ddu (Black Crag), a name which is wholly inappropriate in the sort of weather conditions that make Hidden Gully a very worthwhile outing. Narrow and steep, it exudes atmosphere, and when combined with East Wall Gully, it becomes part of an extremely rewarding direct route from the shores of Llyn Idwal all the way to the summit of Glyder Fawr itself.
Traditionally there has been no culture of claiming the first ascents of winter routes in Snowdonia, so unfortunately the identities of the first ascentionists of this route are unknown.
Conveniently, Glyder Fawr is located very close to the A5 meaning that there isn't a long approach to the bottom of the route.
There is plenty of parking along the A5 near Ogwen Cottage (SH 648 603), some of which you have to pay for, some of which you don't. My advice is to never bother with the official car parks and just park along the roadside. There is a wide 'pavement' type verge on the southern side of the road that can easily accommodate the width of a car or minibus, and is completely free and never full (even on bank holidays). It also allows you to park even closer to the base of the mountain and the start of the path.
Take the path from the Cottage to Llyn Idwal (SH 645 595). Follow the path along the eastern shore southwards. From here you will have a choice of approaches, either traverse in from the left, passing under the Sub-Ceifion Rib (SH 648 592), or better still, climb East Wall Gully, which will take you directly into the Cwm. Providing the weather is clear, Clogwyn Ddu should bow be an obvious feature on the right hand side of the cwm. Make your own way the base of the crag and skirt around it to access the Gully, which is located around SH 646 581 (see photo )
Start by ascending the obvious snowy depression that gives Easy Route (Grade I) in the back corner of the Cwm. A steep narrow gully can be spotted bearing off to the right, just to the right of Clogwyn Ddu. This is your objective.
Pitch 1 (Tech. Grade 1; 50m): From a short way up Easy Route move off diagonally right to the narrow gully.
Pitch 2 (Tech. Grade 2; 50m): Follow the narrow gully to its steep and often corniced exit. A couple of chockstones will likely cause the greatest difficulty.
If conditions are favourable most will not feel the need to use anything more than a single axe and crampons, however, if conditions are a bit more on the icy side, ice tools, a singe rope and a small rack would be very helpful. This being a gully climb, a helmet is also a very good idea.
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