There are two walks here, and both start at Ogwen. The shorter circuit of Llyn Idwal can suit less-experienced walkers who want the cwm without the climb.
The longer loop is 3.1 miles (5 km), in about two hours.
It adds a steep climb towards Twll Du, the Devil’s Kitchen, and suits walkers who are happy on loose rock.
The Eryri National Park Authority, the public authority responsible for the national park, grades it as moderate.
Starting at Ogwen
The walk starts from the car park at the Canolfan Ogwen Centre. Head for the far end of the centre, where a small flight of stone steps leads up to a stone path.
Do not take the quarry trail on your right. Keep to the stone path ahead.
On the way you pass a viewpoint where slate pillars stand in a circle. The Authority’s route sheet suggests looking through the holes in the pillars at the surrounding peaks.
Past the pillars the path goes through an iron gate and over a bridge. It then climbs gradually to a fork. Bear right to reach the shore of the lake.
Round the lake
At the shore, turn left.
The path runs clockwise round Llyn Idwal and passes through a kissing gate.
The ground steepens gradually as you near the far end of the lake. Here the two walks part at a junction.
- Turn right for the shorter route. The Authority describes it as a shorter, less challenging path that avoids the climb towards Twll Du.
- Keep left for the longer loop.
The 5 km and two hours are for the full loop.
Why the cwm is a nature reserve
No place in Wales was designated a National Nature Reserve before Cwm Idwal.
The Authority calls it one of the UK’s finest examples of a hanging glacial valley. Smaller glaciers within the bigger Dyffryn Ogwen system shaped it.
Rare arctic alpine plants grow here, including moss campion, Lili’r Wyddfa and purple saxifrage. The Authority says they survived the Ice Age.
The park asks walkers to keep to the marked paths to prevent erosion.
Dogs should be on leads, especially near livestock and during the bird nesting season.
The climb towards Twll Du
Keep left at the junction and the path steepens. The route sheet lists, in order:
- steep steps
- scree
- a bridge
- the way on towards Twll Du
Take care here, especially if it is icy. The route sheet says the ground underfoot can be very slippery.
The Authority’s route page speaks of crossing loose rock and going around and across large boulders.
Further on you reach a large boulder where the path turns sharply upwards to the left, through about 90 degrees.
Keep following the path.
On the way back down to the lake, take care again. One part of the path scrambles over a few boulders, according to the route sheet.
The shorter route avoids this climb.
If it is the cleft and the ground beyond it that interest you, the path past the Devil’s Kitchen onto the Glyderau is a separate and longer day.
Back to the lake and the bridge
After the descent the path returns to the lake’s shore and runs towards the eastern end. A gate leads onto a gravelly beach, and the slate bridge crosses the water.
Turn left after the bridge and retrace your steps to the Ogwen car park.
Allow about two hours for the full loop, with 140 metres of ascent in all. It is a walk for people with some countryside experience and reasonable fitness, in the Authority’s words.
If you are new to hill paths, the shorter route round the lake is the one the Authority says can suit less-experienced walkers.
If you get into trouble, call 999 and ask for mountain rescue.
We compile and explain public route and safety information. We guide nobody and sell nothing on the hill.
Getting to Ogwen and back
Parking in the Ogwen Valley is extremely limited, especially at peak times. Cars parked on clearways or double yellow lines, or blocking the road, may be removed at the owner’s expense.
The T10 bus runs between Bangor, Bethesda and Betws-y-Coed, with a stop right at Ogwen. The Authority suggests parking at Bethesda football club and catching the bus from there.
The T10 stops at Bangor train station, so a train to Bangor connects with it.
Before you leave home, check the T10 timetable for the last bus back from Ogwen.
