One of the most impressive areas of the National Park’s landscape
Standing in the heart of Cwm Idwal might be the only way of truly experiencing the otherwordly atmosphere that emanates from this small glacial valley.
The crater-like cavity of Cwm Idwal is the result of phenomenal geological activity that took place millions of years ago. It is one of the finest places to witness the aftermath of these forces throughout the National Park.
Cwm Idwal has been attracting climbers, hikers, geologists, biologists, and botanists alike for many years. The most notable of Cwm Idwal’s visitors is Charles Darwin, who conducted much of his scientific work in the area.
Warden’s Walk of the Month
Cwm Idwal is one of the National Park’s gems. Its diverse wildlife, stunning geology and natural beauty attracts all kinds of visitors throughout the year. It’s possible to make a short trip to the lakeside for a family picnic, follow the route around the lake or, if you are an experienced walker, venture over Twll Du (The Devil’s Kitchen).
—Alan Pritchard, Y Carneddau Warden
Snowdonia National Park Authority
Why this path?
This particular route in Cwm Idwal is a challenging route that ascends steeply towards Twll Du (Devil’s Kitchen). Some parts of the path require crossing loose rock and navigating around and across large boulders.
However, Cwm Idwal does offer a route that avoids the ascent to Twll Du (Devil’s Kitchen). This shorter, less challenging path can be suitable for less-experienced walkers.
Snowdonia National Park Authority has categorised this route as a moderate route. It is suitable for people with some countryside walking experience and a reasonable level of fitness. The terrain will include some steep or unsurfaced paths in the open countryside. Walking boots and waterproof layers are essential.
Canolfan Ogwen Centre, Nant Ffrancon (SH 649603)
Relevant OS Map
OS Explorer OL17 (Snowdon and Conwy Valley)
Always park in designated parking places and never in areas where you block entrances to fields or residential areas.
Snowdonia National Park Car Park, Canolfan Ogwen Centre
Owned by Snowdonia National Park Authority
Parking here and elsewhere in the valley can fill up very quickly, we advise that you consider parking in the nearby village of Bethesda and catch the regular T10 bus up to Cwm Idwal.
Geology at Cwm Idwal
Cwm Idwal is arguably one of the best places to see evidence of the tremendous geological events that shaped Snowdonia’s landscape.
450 million years ago, phenomenal geological forces created the towering cliffs surrounding the lake. The fold and faults in the rocks are evidence of these forces.
Glacial activity formed the incredible bowl-shaped landscape of Cwm Idwal. The glacier was part of a more extensive glacial system that created Dyffryn Ogwen. Valleys formed from these smaller glaciers are known as ‘hanging valleys’. Cwm Idwal is one of the UK’s best examples of a hanging glacial valley.
Cwm Idwal was the first designated National Nature Reserve in Wales.
Some of the plants at Cwm Idwal have survived the Ice Age. They include rare arctic alpine plants such as the moss campion, Snowdon lily and purple saxifrage.
The seasonal variety of wildlife at Cwm Idwal makes it a great area to visit throughout the year. During the spring and summer, birds such as the ring ouzel and wheatear settle in Cwm Idwal. The remarkably rare Snowdon lily can also grow on craggy outcrops during these seasons.
The autumn and winter bring hardier plants to the surface, including a range of heathland vegetation and the purple saxifrage.
The name ‘Cwm Idwal’
Both ‘cwm’ and ‘dyffryn’ translate to ‘valley’ in English. However, the word ‘cwm’ has a more distinct meaning. ‘Cwm’ is often attributed to rounded, glaciated valleys such as a corrie or cirque, while ‘dyffryn’ refers to more extensive valleys such as Dyffryn Ogwen (Ogwen valley). Cwm Ystradllyn and Cwm Penmachno are other examples of cwms in the National Park.
The name Idwal derives from the rich history of the princes of Wales. The 12th century Welsh prince, Owain Gwynedd, had a son called Idwal. According to legend, Owain decided to entrust the care of his son to Nefydd Hardd, a Welsh nobleman. However, Nefydd grew envious of Idwal. Nefydd’s son, Dunawd, wasn’t half as clever as Idwal. Dunawd decided to push Idwal into the lake and drowned him.
On hearing the news, Owain banished Nefydd from the ancient kingdom of Gwynedd and named the lake in memory of his son.
It is said that no bird flies over the lake’s surface and that a wailing voice can be heard near the lake during storms.
Darwin at Cwm Idwal
World-renowned biologist, Charles Darwin, visited Cwm Idwal during the first half of the 19th century. His studies at Cwm Idwal would later form part of the most famous publication in science, ‘On the Origin of Species’.
During his time at Cwm Idwal, Darwin discovered that the rocks and boulders in and around the valley held small tiny fossils of sea creatures and marine plant life. His discovery suggested that Cwm Idwal would have at one point been under the ocean.