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.
This event gives participants the opportunity to take in a runnable, beautiful route which follows the North Walian coastline between Prestatyn and Bangor.
An epic challenge, making a full 106km circuit of the Isle of Wight, starting and finishing in Chale, enjoy well stocked rest stops and superb scenery every step of the way.
The full 106km circumnavigation of the Isle of Wight, in daylight hours. Overnight at Cowes for a well-earned rest on this wonderful exploration of the coastal routes around the island.
A demanding challenge, taking on 100km along the UNESCO World Heritage Jurassic Coast, starting from Corfe Castle on a fully-supported challenge visiting the highlights of the region.
Take on the full 100km challenge across two days, to enjoy the entirety of the route during daylight, with camping options at the halfway Basecamp in Weymouth.
Walk, jog or run the journey from Capital to Coast, over the North and South Downs. A fully supported challenge leaving Richmond-upon-Thames for the finish line at Brighton Racecourse.
Walk, jog or run the full 100km London to Brighton route, over two daytime sessions, with an overnight stop at the Basecamp at Turners Hill.
Take on the full 100km challenge, starting from Kendal Base Camp, a fully supported ultra. making a glorious loop of the spectacular south Lakes.
Take on the full 100km challenge during the hours of daylight, split over the two days. Enjoy the whole incredible route, whilst also getting a well-deserved overnight sleep.
Take on a 100km challenge, making a fully supported loop from Cirencester, exploring the picturesque, undulating terrain of the Cotswolds on a spectacular challenge.
Walk, jog or run the full 100km challenge, split over two days, with a well deserved nights sleep at the half way basecamp, to recharge your batteries overnight.
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 a 100km challenge, starting and finishing at the Bakewell Showground on a fully supported exploration of the beautiful Peak District National Park.
Undertake the full 100km challenge, split over two days, to allow a good nights rest and appreciate the glorious scenery during the daytime.
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.
The full distance option of the South Coast Challenge from sunny Eastbourne, over the magnificent Seven Sisters, onto Cuckmere Haven and over the South Downs all the way to historic Arundel.
The full distance option of the South Coast Challenge over 2 days with 57km on day 1 and 43km on day 2, meaning you experience the route in daylight with the chance to sleep overnight.
The full, non-stop option of the Thames Path Challenge from leafy South West London following the river to Hampton Court, Runnymede to finish at Henley-on-Thames for a celebratory finish and BBQ.
The full distance option of the Thames Path Challenge over 2 days with 50km on day 1 and 50km on day 2, meaning you experience the route in daylight with the chance to sleep overnight.
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.
Select your location for 100K ultra marathons in your area.