Ultra-Trail Snowdonia takes runners through the rugged Eryri (Snowdonia) National Park in North Wales, starting and finishing in the slate-mining village of Llanberis at the foot of Yr Wyddfa (Snowdon). With steep, technical climbs, exposed ridgelines and notoriously unpredictable Welsh mountain weather, UTS is widely regarded as one of the toughest mountain ultras in the UK and joined the UTMB World Series in 2022.