Ultra-Trail Snowdonia is a 100km ultra marathon in Llanberis, United Kingdom. Distance: 100km. Elevation: 5,500m D+. Difficulty: challenging (Challenge Rating 58/100). DNF rate: 28%. Time limit: 30h. Surface: trail. Established 2018.
Ultra-Trail Snowdonia
Llanberis, Snowdonia, United Kingdom
"100km through the wild mountains of Snowdonia — three mountain ranges, 5500m of climbing, and famously hostile weather."
A 100km mountain ultra through Wales's most dramatic peaks with technical terrain, navigation challenges, and notoriously unpredictable weather.
The Course
A demanding 100km loop through Snowdonia National Park (Eryri) encompassing the Snowdon massif, Glyderau, and Carneddau mountain ranges. Technical terrain with rocky ridgelines, boggy moorland, and slate quarry trails. Navigation required in parts.
mountainous
loop
8
1,085m
Runner Experience
Standard aid station support with food, drinks, and basic medical assistance at regular intervals.
Post-race gathering with awards, food, and shared stories. The ultra community spirit is strong at Ultra-Trail Snowdonia.
Race Day Weather
10°C
3° – 16°
80%
60%
Welsh mountain weather — expect rain, wind, and poor visibility. Snowdonia receives over 3000mm of rainfall annually. Conditions can be truly hostile.
Stats & Records
2018
300
22:00:00
11:45:33
Damian Hall (2023)
14:12:08
Sabrina Verjee (2022)
Entry
£125
October
weeks
Lore & Trivia
Ultra Trail Snowdonia runs through the mountains of Snowdonia National Park in North Wales — the range that trained Edmund Hillary for Everest and has been the training ground for generations of British climbers. The course traverses Carneddau, Glyderau, and the Snowdon massif through terrain that is steep, technical, and frequently wet. Welsh mountain weather is notoriously hostile, and Snowdonia's combination of exposure and precipitation makes every edition a genuine mountain challenge.
- ▸ Snowdonia was renamed Eryri in Welsh, and the race uses both names.
- ▸ The course traverses all three major mountain ranges in northern Snowdonia in a single loop.
- ▸ Welsh mountain terrain is notoriously boggy — runners can sink knee-deep in peat bogs on the moorland sections.
- ▸ The slate quarry sections near Llanberis add an industrial-heritage dimension unique among mountain ultras.
- ▸ Established in 2018.
Snowdonia in the rain — Welsh slate, cloud, and the mountains that made British mountaineering.
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Frequently Asked Questions
How long is Ultra-Trail Snowdonia? +
Ultra-Trail Snowdonia is a 100km (100km) ultra marathon with 5,500m of elevation gain. The course is loop on trail terrain.
How hard is Ultra-Trail Snowdonia? +
Ultra-Trail Snowdonia is rated challenging with a Challenge Rating of 58/100 (Challenging). The DNF rate is 28%. Runners have 30 hours to finish.
What is the weather like at Ultra-Trail Snowdonia? +
Average temperature is 10°C (range 3°C to 16°C) with 80% humidity and a 60% chance of rain. Welsh mountain weather — expect rain, wind, and poor visibility. Snowdonia receives over 3000mm of rainfall annually. Conditions can be truly hostile.
Are crew and pacers allowed at Ultra-Trail Snowdonia? +
Crew access is allowed. Pacers are allowed after 60km. Mandatory gear is required. Self-navigation is required.
What is the course record for Ultra-Trail Snowdonia? +
The men's course record is 11:45:33 set by Damian Hall in 2023. The women's course record is 14:12:08 set by Sabrina Verjee in 2022.
What is the average finish time for Ultra-Trail Snowdonia? +
The average finish time is 22:00:00. About 300 runners finish each year. The DNF rate is 28%.
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