Distance 21 miles (33.8km)
Classification Challenging
Duration 14 hours over two days
Begins Abergwyngregyn car park
Ends Idwal Cottage youth hostel
OS grid refs SH6572, SH6460
Walk in a nutshell
This two-day walk will take you over two dominant mountain ranges in the Snowdonia national park: the Carneddau and the Glyders. There are some daunting ascents (including Carnedd Llewelyn, the second highest peak in Wales) and descents, and you'll need a map, compass, good boots and clothing.
Why it's special
It includes one of the UK's great descents, the scramble from Pen yr Ole Wen. Throw in amazing views and you've got a walk that will live long in the memory.
Keep your eyes peeled for
The Devil's Kitchen, a blackened cleft in the cliffs. The large ruined cairn at Foel-fras (942m), whose summit may have served as a Neolithic fort. Keep an eye out for feral goats in the Tryfan valley and meadow pipits and cuckoos on the Carneddau.
Stay overnight
Gwern Gof Uchaf (tryfanwales.co.uk) is a campsite and bunkhouse on a working hill farm. No booking required for tents, but do call ahead if you'd prefer to sleep in a bunkbed.
Recover afterwards
The eco-friendly, self-catering Idwal Cottage youth hostel (yha.org.uk/hostel/idwal) has a well-stocked licensed bar.
If it's tipping down
Take a trip 150m underground on Europe's steepest mining cable railway at Llechwedd Slate Caverns (llechwedd-slate-caverns.co.uk).
How to get there
The Arriva route 5 coach (arrivabus.co.uk) runs between Caernarfon and Llandudno Junction bus stations, via Bangor and Abergwyngregyn.
Step by step
Day one
1 Begin at Abergwyngregyn car park at the end of the road above the Afon Anafon river. Follow the track round the north of Foel Dduarth, then the right turn signposted for Drum.
2 Follow the direct path from Drum to the successive summits of Foel-fras, Carnedd Uchaf (or Carnedd Gwenllian), Foel Grach, Carnedd Llewelyn, Carnedd Dafydd and Pen yr Ole Wen.
3 On Pen yr Ole Wen, head due east to follow the track downhill.
4 Head for the ladder over the dry stone wall and continue downhill by the Afon Lloer river to the A5 at Llyn Ogwen.
Day two
1 From Gwern Gof Uchaf car park take the path to the left of the cottage, cross the stile, turn right, then left in front of the gate.
2 Follow the path to the east of Tryfan for 2.5 miles to the valley head. Then take the path through scree diagonally up to the ridge line near Llyn Caseg-fraith. Head west across the summits of Glyder Fach and Glyder Fawr.
3 After Glyder Fawr ignore the first right and turn right downhill in front of the lake Llyn y Cwn.
4 As you walk down the path you see the Devil's Kitchen through the cleft, dropping down to Llyn Idwal. Follow the edge of the lake down to the car park next to Idwal Cottage youth hostel.
