Marathon Eryri takes place on Sat, Oct 24, 2026 in Llanberis, United Kingdom. The main route is 42.2 km.
- Date
- Sat, Oct 24, 2026
- Start
- Llanberis 🇬🇧
- Distance
- 42.2 km
- Level
- Open to all
Marathon Eryri is a demanding and spectacular marathon that encircles Yr Wyddfa (Snowdon), Wales’ and England’s highest peak.
Official event pageWhat this race demands
Marathon Eryri requires sustaining running output over a full marathon distance around the highest peak in Wales and England. The October timing in Great Britain means athletes must prepare for cool and potentially wet autumn mountain conditions.
Distance endurance
The standard marathon distance of 42.2 km demands thorough aerobic conditioning and structural resilience to sustain forward progress over several hours.
Mountain terrain
Encircling Yr Wyddfa requires continuous management of demanding topographical changes, placing significant mechanical load on the lower limbs during sustained climbing and descending.
Weather resilience
An October event in the Welsh mountains exposes runners to low temperatures, wind, and precipitation, requiring careful thermal regulation and fueling management.
A marathon duration exceeding two and a half hours requires consistent intake of 60 to 90 grams of carbohydrates per hour to maintain glycogen availability.
What would it take you?
Pick the level closest to yours for an estimate of finish time on this course and the training a solid preparation needs.
Estimated finish
3:45–4:30
Peak-week training
5–7 h/week
A model estimate from distance, climbing and level, not a promise. Conditions, drafting and pacing move it.
IntervalCoach turns those weekly hours into a concrete plan built around your actual fitness. Start with this race as your goal
Your road to race day
Race day at Marathon Eryri is 9 weeks away. This is how a coach divides that time. The first phase starts now.
01Build3 weeks · Aug 23, 2026 – Sep 12, 2026
Progressive overload: training load climbs in waves, with harder weeks stacked on the base and planned recovery weeks that let the gains land.
02Peak3 weeks · Sep 13, 2026 – Oct 3, 2026
The hardest weeks of the plan: race-specific intensity at nearly full training load, sharpening exactly what this race asks for.
03Taper2 weeks · Oct 4, 2026 – Oct 17, 2026
Volume drops while intensity stays: short, sharp efforts keep the legs awake as fatigue drains away.
04Race week1 week · Oct 18, 2026 – Oct 24, 2026
Openers, rest and logistics. The work is done; the job now is arriving fresh.
Similar races
Organising this race?