Cadair X Half Marathon

Tackle one of Britain's most demanding and spectacular mountain races at the Cadair X Half Marathon on Saturday, 17th October 2026, a brutally beautiful 13.1-mile loop ascending to the 893m summit of Cadair Idris in Snowdonia. This UTMB-indexed race wastes no time, throwing runners into a punishingly steep climb through ancient woodland and a dramatic gorge within the first 3km, before revealing breathtaking views of glacial lakes and the rugged Welsh peaks. The technical and exposed terrain, particularly on the rocky descent from the summit, demands respect, solid mountain fitness, and appropriate kit, with a strict 90-minute cut-off at the top to ensure runner safety. Starting and finishing at the iconic Cadair Tea Room near Tal-y-llyn lake, the route is fully marked but requires self-sufficiency, with checkpoints providing vital water, electrolytes, and food on the long descent back through tranquil forests and past hidden waterfalls. With a fiercely competitive field chasing the course records and a supportive atmosphere among those taking on this serious challenge, Cadair X represents the pinnacle of British mountain running. Whether you're an elite fell runner or an experienced trail athlete seeking an unforgettable autumn test, the 2026 edition promises raw adventure, stunning scenery, and the profound satisfaction of conquering a true Welsh giant.