100K ultra runs in the UK
The middle of the common ultra distances at just over 60 miles, 100K ultra marathons are a big step up from the marathon. Despite this, distance is not always the key challenge with ultra runs - the total ascent gives a much better indication of how hard it will be. Select your location to find 100K ultra runs in your area or scroll down to browse events coming up.
Search by month
Search by place
London
South East
South West
East of England
East Midlands
West Midlands
Yorkshire
North East
North West
Scotland
Wales
Northern Ireland
Jersey
100K ultra runs in 2025
Featured events are listed below - select a month/region or the map view to see all events.
- Sat 21 - Sun 22 Jun
- £39-£199
Cotswold Way Ultra Challenge
Challenge yourself in the rolling hills of the Cotswolds featuring the Cotswold Way itself, villages, footpaths and trails with fabulous views on route plus full support and hospitality.
- Trail run 2
- Ultra run 4
- 100K ultra run
- 10K run
- Sat 28 - Sun 29 Jun
- £39-£199
Peak District Ultra Challenge
From the idyllic basecamp hub in Bakewell, charity challengers will head into the fabulous Peak District National Park on a route from 10 miles right up to the full 100km with full support!
- Ultra run 3
- 100K ultra run 2
- Trail run 2
- Sat 12 - Sun 13 Jul
- £85-£270
Race to the Stones
Conquer Britain's oldest trail, the ancient Ridgeway, at the UK's biggest ultramarathon as you race towards the 5000-year-old Avebury Standing Stones. Back for the 12th Year Running!
- 50K ultra run 2
- 100K ultra run 3
- Sat 12 - Sun 13 Jul
- £121.99-£251.99
Black Diamond Yr Wyddfa Snowdon24
Yr Wyddfa (Snowdon) is the highest mountain in England and Wales. Your challenge is to ascend and descend as many times as possible in 24 hours - solo or as a relay team.
- 24 hrs trail running + 3182 ft ascent
- Sat 19 - Sun 20 Jul
- £39-£199
Gower Peninsula Ultra Challenge
A new Ultra Challenge for this year, set on the stunning Gower Peninsula – the UK’s first Area of Outstanding Natural Beauty and famous for its golden beaches.
- 100K ultra run 2
- Ultra run
- 50K ultra run 2
- Marathon
- Multi-terrain run
- + 1 more race
- Sat 6 - Sun 7 Sep
- £89-£199
South Coast Ultra Challenge
The South Downs National Park is a superb backdrop for a real challenge featuring Beachy Head, the Seven Sisters and the South Downs Way with a choice of distances from 25km right up to 100km!
- 100K ultra run 2
- Ultra run 2
- Trail run
- Fri 12 - Sun 14 Sep
- £39-£199
Thames Path Ultra Challenge
England’s greatest river provides a fantastic backdrop for an unforgettable 'festival' challenge weekend, with distances from 10km right up to 100km there’s a Thames Challenge for everyone!
- 100K ultra run 2
- 50K ultra run 2
- Trail run 4
- Ultra run
- 10K run
- + 4 more races
- Fri 19 Sep
- £80
Peak District Challenge | Gold Ultra 100K
A hilly and challenging route showcasing the best of the Peak District for those who can maintain 4kph over 24 hours. Night navigation experience is essential.
- 100 km trail running + 3300 m ascent
- Sat 25 Apr 2026
- £90.50
North Wales 100K
This event gives participants the opportunity to take in a runnable, beautiful route which follows the North Walian coastline between Prestatyn and Bangor.
- 100 km trail running + 8000 ft ascent
- Sat 23 Aug
- £90-£108
Run the Borders | Full 109K
Visiting the heartland of the Scottish Borders, runners and walkers will take to the Borders Abbey Way to complete the full waymarked loop as individuals, teams or a relay of four.
- 109 km trail running
100K ultra runs near you
Select your location for 100K ultra marathons in your area.