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.
Featured events are listed below - select a month/region or the map view to see all events.
Take on 50 historic miles across the beautiful Southern Upland Way - one of the greatest trails in the UK. Ultrarunners will tackle several ascents, pass through forests, valleys and by lochs.
Take on the full 100K Race to the King ultra marathon challenge in one go. Fully supported through day and night on a route combining castles and coastal scenery.
Take on the full 100K Race to the Stones ultramarathon in one go. Fully supported through day and night on an incredibly scenic and historic route.
Take on the full 100K Race to the Stones ultramarathon with an overnight stop at the all-inclusive Basecamp, meaning a good nights' sleep in between the 50K stints.
Take on the full Race to the Stones 100K ultramarathon over two days, making your own arrangements for overnight accommodation at the halfway point.
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.
Select your location for 100K ultra marathons in your area.