Snowdonia Skyline

The Snowdonia Skyline is one of the most ambitious mountain challenges in Wales — a circuit of the principal mountain ranges of Snowdonia in a continuous run. It extends the Welsh 3000s concept into a much longer route by incorporating the southern ranges (Cadair Idris, the Rhinogydd and Moelwynion) that lie outside the 3000-foot threshold.

At around 97 km with 7,500 m of ascent, it is a genuine ultramarathon-length challenge with sustained exposure on serious mountain terrain. The route is not standardised — several variations exist — but most versions take in Yr Wyddfa and the Snowdon horseshoe, the Glyderau and Tryfan, the Carneddau plateau, then loop south to the Moelwynion and Cadair Idris before returning north.

Completion within 24 hours is the traditional target, achieved by a relatively small number of runners. Most take 18 to 30 hours.

Snowdon group: Yr Wyddfa (1,085 m), Crib Goch, Crib y Ddysgl — the full horseshoe. Descend to Pen-y-Pass.

Glyderau: Glyder Fawr (1,001 m), Glyder Fach, Tryfan (914 m). Descend to Ogwen.

Carneddau: Pen yr Ole Wen, Carnedd Dafydd (1,044 m), Carnedd Llewelyn (1,064 m), Foel-fras. Descend south.

Moelwynion: Moel Siabod, Cnicht, Moelwyn Mawr (770 m), Moelwyn Bach. Rough, remote ground.

Cadair Idris: Penygadair (893 m) — the southern anchor of the route. Long return north.

The point-to-point nature (Cadair Idris is 45 km south of Snowdon) requires either a circular route or a car shuttle. Most runners tackle it as a circuit starting from Llanberis or Pen-y-Pass.

Support crew access: Ogwen car park, Pen-y-Pass (limited), Capel Curig, Blaenau Ffestiniog, Corris (near Cadair Idris). The Cadair Idris section requires driving support down the A470.

Best time: June to August for maximum daylight and best mountain conditions.