SNPA Strapline

Visiting Snowdonia


Cwm Idwal, Ogwen

Cwm Idwal is a very popular attraction for visitors interested in walking, climbing, fishing and geology. Llyn Idwal is 800 metres long and 300 metres wide.

The valley was scooped out by ice thousands of years ago and is one of the best examples of a glacial valley in Wales.

During the 12th century, Owain, prince of Gwynedd, decided to entrust the care of his son Idwal to Nefydd Hardd. Nefydd was envious of clever Idwal because his own son Dunawd was untalented. Dunawd decided to push Idwal into the lake so that he would drown. Owain banished Nefydd from the kingdom of Gwynedd and named the lake Idwal 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 when there is a storm in the Cwm.

Snowdonia Upland Path Partnership
The Snowdonia National Park Authority, the National Trust and the Countryside Council for Wales work together, with the aid of Objective One European Funding, to look after the paths and ensure that visitors leave as little trace as possible of their visit. The number of visitors is monitored in order to ensure that paths are managed according to the number of visitors who use them.

Distance: 3 miles - 5Km

Ascent: 460 feet - 140 metres

Time: About 2 hours

Grade: Moderate Walk

Start/Finish: Ogwen Warden Centre, Nant Ffrancon, Bethesda (SH 649 603)

Parking: Pay & Display car park at Ogwen Warden Centre

Post Code: LL57 3LZ

Relevant Map: OS Ordnans Exp OL17 (Snowdon & the Conwy Valley)

This map is intended as a rough guide only. You should use the most recent version of the relevant Ordnance Survey map (see above) when walking the route.

Route Details

1. From the car park, keep left past the Warden Centre and Information Room and follow the path up towards the iron gate. This gate was designed by Joe Roberts, one of the National Park’s Seasonal Wardens, as a tribute to Evan Roberts, who was appointed first Warden of Cwm Idwal in 1953. Dylan Parry was the blacksmith responsible for producing the tactile gate. The top part reflects the topography around Twll Du whilst the rails reflect the geology of the area and the reflection of the moraines in Llyn Idwal.

2. Follow the path whilst enjoying the splendid view of mountain peaks and sharp ridges as you approach Llyn Idwal. Look east towards the mountain of Tryfan. Can you see a reclining facial image? Some say that they can see a Neolithic man; others see an Indian chief with headdress whilst the young at heart might see a Homer Simpson look-alike!

3. When the path evens out, look west to enjoy the view of Nant Ffrancon and the slate village of Bethesda in the distance. To the east is Nant y Benglog and Llyn Ogwen.

4. Follow the obvious path to the left in order to start your walk around the lake. Every year, 350,000 visitors come to enjoy Ogwen Valley and it is therefore vital to protect the area and prevent erosion.

5. As you follow the path, look over the lake towards the mounds on the northern shore. These are moraines which where left behind when the glaciers melted. According to legend these are the burial mounds of Idwal and his men.

6. The path becomes gradually steeper as you approach the eastern end of the lake. The slabs lying at an angle of 50° are the famous Idwal Slabs. The Welsh name for these is ‘Rhiwiau Caws’ which literally means ‘Slopes of Cheese’. They were first climbed in 1897 by Rose and Moss and are primarily used as an introduction to climbing for beginners.

7. Carry on along the path and make your way up the steep steps and across the scree towards Twll Du. At one stage the path crosses a small waterfall. Please take care especially if it is icy as the stones can be very slippery. Once you climb the steep stone steps, you will be in the midst of the large boulders by Twll Du, peeled off the cliff by the retreating glacier.

8. Follow the stone steps down to the other side of the lake. Can you see plots of land which have been fenced in on the northern shore? Since 1957 this has been the site of trials to exclude grazing from certain areas to see which vegetation can survive. Can you see any sheep or cattle grazing in Cwm Idwal? There is currently an agreement between the National Trust, Snowdonia National Park Authority and the Countryside Council for Wales that there should be no grazing allowed in the valley because of a long term study in creating a more ‘natural’ vegetation.

9. The path leads down to the shores of the lake and then on to the bridge and the path which will lead you back down to the car park.

360 Panorama View

Cwm Idwal

  • Cwm Idwal

    Cwm Idwal (© Crown copyright (2014) Visit Wales)

  • Cwm Idwal

    Cwm Idwal (© Crown copyright (2014) Visit Wales)

  • Cwm Idwal

    Cwm Idwal (© Steve Smith)

  • Cwm Idwal

    Cwm Idwal (© Jan Davies)

Safety Note

Please read our Mountain Safety Advice before venturing out on the mountain.

Please Remember

Though you are in the Snowdonia National Park, please remember that the path passes through privately owned farm and grazing land, where dogs are not welcomed unless under close control or on a lead.