Always Aim High Events has opened entries for Snowdonia Trail Marathon Eryri 2027. The weekend returns to Llanberis on 10 and 11 July, with Super Early Bird prices until midnight on Sunday 13 September.
There are four races across the weekend:
- 10K on Saturday 10 July
- Half marathon on Sunday 11 July
- Marathon on Sunday 11 July
- Ultra on Sunday 11 July
The launch comes after two summers in which heat wrecked the meeting. In 2025 the races were stopped at 12.25pm on Saturday 12 July, with the 10K, half, marathon, ultra, Yr Wyddfa 24 and the XTERRA Trail Run World Championship all halted. Many 10K and half marathon runners had already finished. In 2026 Always Aim High called it off the night before, after a 6pm safety meeting on Friday 10 July. The decision came at 7pm, runners were told at 7.30pm, and on course readings had hit 34°C, hotter than the forecast.
Chief executive Matt Newman said after the 2025 stop: “Having delivered this race in Llanberis for the past ten years, we are deeply saddened to have had to halt the event. The safety of our participants has always been our top priority, and we made the decision to halt the races to ensure everyone was brought down from the mountain safely.” The 2026 call was framed the same way. The Medical Director warned about exertional heat illness on a remote mountain course, and the organiser said the assessment was about a mass participation event, “rather than the capabilities of individuals.”
The July date is staying put. Always Aim High says the race has sat on this weekend for more than a decade, and that 2026 was exceptional, with other outdoor events nearby running the weekend before and after without the same extreme heat. What has changed is the courses. More of the serious climbing now comes earlier in the day, which the organiser says gives the team more room to adapt if temperatures spike and to keep runners off the hardest ground in the hottest hours.
Super Early Bird prices, affiliated then unaffiliated, plus Let’s Do This fees, are:
- 10K: £30.99 / £32.99 (plus £1.86 / £1.98)
- Half marathon: £45.99 / £47.99 (plus £2.76 / £2.88)
- Marathon: £60.99 / £62.99 (plus £3.66 / £3.78)
- Ultra: £96.99 / £98.99 (plus £5.82 / £5.94)
A bundle with the ABP Newport Marathon on 18 April 2027 is £117 plus a £7.02 fee, a £10 saving on two Welsh marathons. Payment plans are available. Runners caught by the 2026 cancellation have been told to check their inbox for a preferential 2027 rate.
The Trail 10K Eryri starts and finishes in Llanberis and packs about 400m of climbing into 10km, with two support points. From around 6.5km it runs into Dinorwig Quarry, part of the Slate Landscape of Northwest Wales UNESCO World Heritage Site, before the drop back to the event village.
The half marathon is the clearer mountain test: about 21km (listed as 12.9 miles) with around 1,250m of climbing. The 2027 line goes most of the way up the Llanberis Path towards Bwlch Glas, high above Clogwyn Du’r Arddu, then takes a short descent on the Ranger Path before dropping onto a more southerly route. There is a feed station above the southern end of Llyn Cwellyn, then another climb to recross the Ranger Path and a return through Bwlch Maesgwm. Always Aim High says the revised layout is built to give more support along the way.
The marathon is about 44km (27.3 miles) and now runs the classic Eryri circuit in a new direction. Runners climb the Llanberis Path on Yr Wyddfa, peel off down the PYG Track, and head through Nant Gwynant towards Beddgelert, then around the western side of the massif towards Rhyd Ddu before the long haul back to Llanberis. The organiser is clear the last section still has teeth.
The Ultra Trail Marathon Eryri is the biggest day of the weekend: about 56km with around 2,300m of ascent, UTMB indexed, and worth 3 ITRA points. Climbing onto Yr Wyddfa comes early, close to 1,000m above sea level, before a much wider loop through valleys, forest and remote trails. Dinorwig Quarry arrives at around 47km. Always Aim High says the 2027 ultra keeps the wild character but allows more room for runner support and course management.
Usual start times, confirmed in final instructions 10 days out, are 5am for the ultra, 6am for the marathon, 7am for the half and 8am for the 10K. Cut-offs are strict.
- 10K: 2 hours 30 minutes
- Half: Bron y Fedw (12.5km) in 3 hours 25 minutes; finish timing ends after 5 hours 15 minutes
- Marathon: Finger Stone of Yr Wyddfa (7.1km) in 2 hours, then diversion onto the half; Beddgelert (24.8km) in 5 hours; Bron y Fedw (35km) in 6 hours 45 minutes; finish timing ends after 8 hours 15 minutes
- Ultra: marathon/ultra split (21.8km) in 4 hours 40 minutes, then diversion onto the marathon; Beddgelert (28km) in 6 hours; Bron y Fedw (38.5km) in 8 hours; 45.3km in 9 hours 15 minutes, then diversion onto the marathon; finish timing ends after 11 hours 30 minutes
Enter this weekend if you want the launch price.
