Snowdonia 3000s / Welsh 3000s

The Welsh 3000s is one of the classic mountain challenges in Britain. All 15 summits over 3,000 ft in Snowdonia lie in three groups: the Snowdon massif, the Glyderau and the Carneddau. The full traverse links them south to north (or north to south) in a single continuous run of around 48 km.

The route was first completed in under 24 hours in 1919. Today it is a well-established fell running challenge. Elite runners have covered it in under five hours; most trail runners take eight to twelve hours. The crux is the descent off the Snowdon horseshoe and the long crossing to the Glyderau, which involves a descent to valley level and a significant re-ascent.

Navigation between the Snowdon group and the Glyderau is the key decision: the direct line via Pen-y-Pass is most common. The Carneddau section is the most physically demanding leg — a long plateau with 15 km of ground to cover above 900 m.

Snowdon group (south to north): Start at Rhyd-Ddu or Pen-y-Pass for Yr Wyddfa (1,085 m), then Garnedd Ugain, Crib Goch. Descend to Pen-y-Pass.

Glyderau: Ascend to Glyder Fawr (1,001 m), Glyder Fach, Tryfan (914 m) — which requires scrambling to reach the summit boulders. Descend to Ogwen valley.

Carneddau: Ascend Pen yr Ole Wen, Carnedd Dafydd (1,044 m), Carnedd Llewelyn (1,064 m — highest in Wales outside Snowdon), Yr Elen, Foel Grach, Garnedd Uchaf, Foel-fras (942 m). Descend north.

Most runners use a car shuttle or support crew between Pen-y-Pass, Ogwen and the Carneddau finish near Aber.

Public transport: Snowdon Sherpa buses run between Llanberis, Pen-y-Pass and Nant Peris. The Carneddau finish is less accessible by public transport — Abergwyngregyn or Llanfairfechan are the nearest villages with bus services.

Best time: May to September. The traverse is very serious in winter conditions. The Crib Goch ridge is dangerous in ice, requiring an ice axe and crampons.