Cwm Idwal

Cwm Idwal was Wales’ first National Nature Reserve (NNR). Officially recognised in 1954 by the Nature Conservancy, it is one of the finest places to see how glaciation and post-glacial processes shaped our dramatic landscape.

The cwm forms a magnificent amphitheatre behind the glacial lake of Llyn Idwal and forms part of the Glydeiriau and Cwm Idwal Site of Special Scientific Interest (SSSI).

Grid Ref: SH642590 Area: 403.30 hectares

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Visiting

There is open access on the reserve with several walking and rock scrambling routes leading up to higher ridges.

The rock scrambling access is a little rougher though. All routes are uneven underfoot, with stiles and gates where the routes cross walls and fences.

Photo by Mike Alexander, ©CCW

Photo by David Woodfall©

The terrain is difficult even under good conditions due to the very steep and rocky nature of the rugged terrain. Visitors should also note that conditions can vary dramatically with the seasons.

How to get there

The A5 passes Llyn Ogwen, within just half-a-kilometre of Cwm Idwal, some seven kilometres south of the village of Bethesda.

A National Park car park is at hand with marked disabled bays - and informal parking is available in lay-bys further south along the main road.

Public Transport
The area is served by the S6 bus service, which runs along the A5 between Bangor and Betws y Coed.

Photo © CCW

Check Gwynedd Council’s public transport information on their website at www.gwynedd.gov.uk or contact Traveline Cymru on 0871 2002233

Facilities

Photo ©CCW

Toilet facilities are available in the car park at Llyn Ogwen.

Who looks after it?

The National Trust, Snowdonia National Park and CCW all co-operate in managing Cwm Idwal and the provision of information.

Photographs by Mike Alexander©CCW

This is a beautiful and important Welsh landscape, and it is easy to see why there are benefits to such shared management:

Is owned by the National Trust
Lies within the heart of the Snowdonia National Park
Is a National Nature Reserve managed by CCW

You can contact the National Trust Welsh Regional Office on 01492 860123

You can also reach the Snowdonia National Park Authority on 01766 770274 or email them at parc@snowdonia-npa.gov.uk

Finally, you can contact the CCW northern region reserves team via the enquiries help line on 0845 1306229 or by email at enquires@ccw.gov.uk. You can also write to us at the address under ‘Contact the team’.

Wildlife

The cold slopes of the cwm are home to communities of arctic-alpine plants, here at one of the southern extremities of their range in Britain. Botanists and enthusiasts can get excited about such rarities like:

Purple saxifrage
Starry saxifrage
Moss campion
Globe flower
Snowdon lily

Other habitats include the lake itself, with beds of reeds and horsetails, and the wet hollows scattered throughout the Cwm which are home to:

Cotton grass
Mosses
The tiny sundew [insectivorous]

Further up on the screes the parsley fern grows, and on the ridges tough plants stand up to the harsh, exposed conditions, like:

Dwarf willow
Stiff sedge

Upland birds in spring include the:

Wheatear
Ring ouzel

Other birds frequent the crags throughout the year, including:

Raven
Peregrine

Rare beetles abound on Cwm Idwal - visitors can also keep on the look out for herds of feral goats.

Photo © CCW

Since 1998 the Countryside Council for Wales, in partnership with the National Trust, have implemented a long term management programme to remove sheep grazing from the whole of the site.

This helps protect and maintain the intriguing plant species and communities that are of national - and international - importance.

We can help ensure such care through shepherding of sheep, which may have entered the NNR from adjacent land outside.