The Cadair Idris Half Marathon

The Tyn Y Cornel Hotel, Talyllyn, Snowdonia

Organiser's Description

The Cadair X Idris Half Marathon is one of the toughest half marathons in the UK, and probably the most awe inspiring. The route takes you through ancient woodland, past stunning glacial lakes, along historic trails, and across challenging mountainous terrain, including the summit of one of Snowdonia's most iconic mountains, Cadair Idris.

This challenging, stunning route, starting from the Tyn-Y-Cornel Hotel in Talyllyn, in the Snowdonia National Park, is 14 miles (23km) with 3720 feet (1140m) of height gain. ​Be one of the first to take on this challenging yet stunning route.

Start Time



08:15 - 09:15​


  • Half Marathon
    £35 BOOK

Event parking

Race timing

Natural Resources Wales Race License

Marked course

Nutrition/water stations

Staffed checkpoints

Prizes & medals

The Tyn Y Cornel Hotel, Gwynedd LL36 9AJ.

The route is longer than a standard half marathon; 14 miles (23km) with 3720 feet (1140m) of height gain. Expect steep ascents and technical and varied descents.

Your usual hill running kit must include:


Personal medication

Drinking vessel

Suitable rucksack/bum-bag


Fully charged mobile phone

A wristwatch

Suitable footwear

Waterproof jacket*

Map & compass*


Sun cream*

Waterproof bag*

Insulation layer*

* Weather dependant - we will inform all participants if any kit may be omitted 24 hours in advance of event start time.

All participants must have the Race Director's number stored - 07725416134

There will be nutrition available at the Check Points (CP):

CP1 - Turn off to Mynydd Moel (4.5km) - Jelly Babies

CP2 - Summit of Cadair Idris/Cut-off point (7.5km) - Jelly Babies

CP3 - Turn off from the Pony Path (10km) - Jelly Babies, Water

CP4 - Mary Jones Chapel (16km) - Jelly Babies, Water, Crisps

CP5 - Forest (19km) - Jelly Babies, Water, Crisps

It is paramount that no litter is left on the route. If you are using your own nutrition please carry out wrappers or leave with the marshals at the Check Points. Any participant seen deliberately littering will be disqualified.

If you have not reached the summit of Cadair Idris within 2hrs 30mins of the event start time you will be asked to turnaround and return to the event start. The summit of Cadair Idris is around the 7.5km mark, after the vast majority of the ascent.

If you have not reached Mary Jones' Chapel within 4hrs 30mins of event start time you will be retired from the event and transported back to the event start. Mary Jones' Chapel is at the 16km mark.

These cut-offs are in place for the safety of participants and marshals. If you have any questions regarding the route or the cut-off times then please get in touch

Sorry, booking has closed for this event 🙁

Booking closed on You may still be able to book a place on the event website.


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