Yr Wyddfa Sea to Summit

Yr Wyddfa Sea to Summit Mountain Ultramarathon

The event is a one day, mass participation run and trek on 26 September 2026. The route covers 29 miles (47 km) with approximately +5600 ft of ascent and moves from sea level to the summit of Yr Wyddfa.

The course begins inside Caernarfon Castle and finishes at Bron y Feds Uchaf, Rhyd Ddu LL54 7YS. The route is fully waymarked with bright orange arrows so participants do not need to follow a GPX file or read a map. The planned ascent approaches the summit via the Watkins Path and the South Ridge, with descent via the Ranger Path, passing through Beddgelert on the southern side of the mountain.

Support and safety provision includes professional event medics and a qualified medical team of paramedics and doctors operating from vehicles and a private ambulance. Pit Stops are positioned along the route to offer toilets, medical assistance, water, hot drinks, salty snacks, sweets and fruit; these are intended to augment personal nutrition plans rather than replace them.

Cut-offs are applied using a 3 mph completion pace; the last Pit Stop before the summit is at about 20.8 miles. From Pit Stop 2 there is an alternative shorter summit route that reduces the total distance to about 20.5 miles with roughly 5175 ft of ascent. The organiser reserves the right to change the course for safety or operational reasons.

Participants must be 18 or over on the day of registration. Fundraising options include a refund offer for specified charity targets and a Trilogy medal is available for completing all three Sea to Summit events. Visit the organization's website for the most recent information.