100K Non-stop
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Macmillan Cancer Support | Race to the King | 100K Non-stop

No one should have to face cancer alone. Support this great cause and join the Macmillan Cancer Support team taking part in 100K Non-stop on Saturday 21 June. Sign up today for £40!

  • Sat 21 - Sun 22 Jun 2025

100K Non-stop


Sign up £40

Fundraise £500

Age 18 & over


Explore the South Downs National Park on this epic ultramarathon offering stunning 50K or 100K routes from the glorious West Dean Gardens and taking in the Monarch's Way.

Expect a superb level of support and organisation with fantastic overnight options at the all-inclusive Basecamp.

Arundel Castle


  • A route steeped in history

    Take the Monarch’s Way to the ancient coastal village of Bosham and on to the mighty Arundel Castle.

  • Support fit for a King

    Race like royalty with pit stops packed with food and expert support throughout.

  • A wide variety of trails

    Two different loops taking in coastal trails and the South Downs National Park.

  • Fun for the whole family

    Bring the family to cheer you on and explore the impressive gardens and sculptures of the West Dean Estate.

  • Effortless logistics

    The figure-of-eight loop makes the simplest possible format to tick off 100km.

This event is part of Race to the King.

Event video

  • Average fitness
  • Event village
  • Families
  • Free venue entry
  • Newcomers
  • Spectators
  • Teams

2025 details to be confirmed.

Fitness level

Anyone can take on ultra marathons. Especially you.

Let's bust the myth that ultra marathons are for elite athletes only. Naturally, some people think they are are only for maniacs, experienced in sprinting up snow-topped mountains and crossing vast, barren deserts. But try telling that to the participants! They are mums and dads, nurses and teachers, grandparents and students. They are weekend hikers, post-work yoga masters and two-wheeled commuters. One thing they all share is the belief that more is in them, and with the support of each other, they will make it to the finish!

This challenge will not be easy and it will require a commitment from you to train and prepare for the event, but with enough focus and support, anything is possible.

Are ultra marathons only for elite athletes?

This event has been designed to be a challenge, whatever your fitness level. More serious runners aim for a specific time while for others completing the distance is the goal. Whichever you are, with the right preparation, you can do it!

The aim is for all walkers and runners to cross the finish line with an unimaginable sense of achievement and a lifetime of amazing memories.

I don’t have enough time to train!

Training isn’t easy! Juggling family and social life and work is no walk in the park, however, this event is planned to make your journey as smooth as possible. Above all, you will have an incredible crew and the most incredible community to share the experience and keep you motivated from sign-up to start line.

Training. Where do I start?

Taking on your first ultra uarathon can be daunting to say the least. However, from sign up to start line you will be supported every step of the way, with training plans for walkers and runners, tips, and great offers from partners. You also get access to an incredible Facebook support forum where you can find nearby walkers and runners to help you train, share advice or just share your blister photos!

Get social

If you're unsure what kit to take or you're looking for a training partner or someone to walk the trail with, join the Trail Series Facebook forum and chat with fellow ‘racers’.

Team challenge

  • Enter a team from 10 to 100+
  • This is the perfect corporate event
  • Accommodates all ages, experience and fitness levels
  • Walk or run a variety of distances
  • Options to camp overnight or take it on in one go

Whether it’s a small group of you or most of the company – there's a package for you. Optional extras include hospitality zones, bespoke kit and live Q & A’s for your team.

Teams encouraged

Team benefits

  • A healthier, happier and engaged workforce
  • Team building across seniority levels
  • Investing in your people’s physical and mental health
  • Raising money for your chosen charity
  • Bonding with clients in a unique and active way
  • Empowering your team with a greater sense of self esteem, optimism and resilience

Easy team admin

The admin is light! The participant comms ensure your team has all the info it needs, as well as being on hand to answer any questions. All the training guides and kit lists are provided, plus there's help with the logistics of getting to and from the event.

  • Bag storage
  • Bar
  • Cafe
  • Camping
  • Entertainment
  • Free parking
  • Music
  • Park
  • Rural
  • Showers
  • Toilets

Event HQ

West Dean Gardens
West Dean
Chichester, West Sussex
West Sussex
PO18 0RX

On the southern edge of the South Downs National Park, West Dean Gardens offer a superb rural location for the Event Village.

By road

Easily accessible by road, lying a short distance from the A27, it's reachable from Portsmouth, Southampton, Brighton and London.

By rail

The closest rail station is Chichester.


There is a drop off zone at the start, where friends and family are able to wait and watch competitors depart from the start line.

  • Check points
  • Cut off time
  • First aid
  • Food stations
  • Marshals
  • Out and back
  • Toilets
  • Undulating
  • Water stations
  • Wave start
  • Way markers

Designed to challenge the most experienced ultra participant, whilst providing the perfect entry point for those taking on their first ultra-marathon. The 100K takes you on a journey to the coast before looping back to West Dean Gardens and out towards Arundel Castle and the heights of the South Downs.

Journey to the coast before looping back to West Dean Gardens and out towards Arundel Castle and the heights of the South Downs.

  • Public transport links
  • Recycling
  • Sustainability policy

The organiser's sustainability framework highlights that sustainability is embedded in all events they organise, including this one. They believe passionately that their events should strive to have as positive impact on the natural world as they do on the teams and individuals that participate in them.

The clear framework is underpinned by the vision to have a net positive impact on the natural world. This will be achieved by:

Sustainability framework

  • Reducing the negative impact of the events

    1. Reducing: Implementing strategies to reduce the negative environmental impact of the events (emissions, ecological impact, water use, plastic pollution).

    2. Off-setting: Off-setting the carbon footprint of the business through initiatives that reduce emissions locally and globally.

  • Increasing the positive impact of the events

    3. Inspiring: Inspiring social and industry behaviour change by sharing, promoting and advocating for partnerships with suppliers, sponsors, clients, participants and the public.

    4. Advancing: Quantifying the impact of the events and setting SMART objectives. Basing strategies on science and sharing data within the Infront Group, the industry and academia.

This framework is regularly reviewed and is available in greater detail.

  • Chip timing
  • GPS tracking
  • Map
  • Medal
  • Post-race meal
  • Training plan

There are well-supported ultra marathons and then there is this one.


  • Training plans tailored to your package and level
  • Top tips from trail running experts
  • Exclusive offers from event partners and suppliers
  • Team on hand to answer any questions you may have
  • Community with access to the event forums to ask questions and share advice

On the trail

  • Fully signposted trails for navigation in day and night conditions
  • Routes through heritage sites, AONBs and along National Trails
  • Pit stops with heaps of food, drink, toilets, medical (and emotional) support
  • Route checking and support throughout the event
  • All routes and wave timings planned for minimal bottle-necks
  • Individual chip timing throughout the event
  • Event photographers at all the top spots along the trail


  • Independent event and route risk assessments
  • Rapid response paramedic teams throughout the event
  • Qualified medical personnel at all pit-stops
  • Medical clinics at the basecamp and finish points
  • Centralised event control system for runner emergencies
  • Additional support contingencies for extreme weather events

Food and drink

  • Fully stocked pit stops including cereal bars, chocolate, sweets, fresh fruit, crisps, sandwiches, tea, coffee, porridge and more
  • A mix of water, squash and flat coke at stops along the way
  • Hot meals at halfway and a hot meal at the finish
  • Cooked and continental breakfasts for those camping overnight
  • Sports nutrition including electrolyte, hydration and recovery products from High5
  • Additional food concessions at the start, halfway and finish for supporters
  • Bars at the basecamp and at the finish
  • Offerings for special dietary requirements throughout


  • Bag transfer to daily finish point for all runners and walkers

The finish

  • Top quality finisher’s medal
  • Live MC welcoming you over the line
  • Finish line photographer
  • Hot meal when you cross the finish line
  • Hot showers for all participants
  • Spectator zones at the finish with food and drink concessions
  • Onward shuttle options
  • Merchandise stand
  • Bag collection

Optional extras

  • Event merchandise
  • Shuttles to and from the start and finish
  • Parking at the start and finish
  • Individual trackers
  • Individual event photos


  • Full refunds

  • Age 18 & over
  • Entries open
  • Charity entries not yet open
  • Charity places
  • Enter online
  • Event merch available
  • Full refunds
  • Insurance available

Refunds, deferrals, transfers

Your money is secure with refund, deferral and transfer options:

  • Full refunds (excl. booking fee) in the case of event cancellation
  • Deferral options if you can’t make the event
  • Participant transfer options if you can’t make the event
  • Enhanced booking insurance as an optional extra on registration


Absolutely fantastic weekend, friend and I ran this as our first and definitely not our only Ultra. Loved the friendliness of other runners, the pit stops were amazing - well stocked with a great selection of food and drinks. We particularly appreciated the clean portaloos!! Aileen

The beautiful landscape of the South Downs Way was a revelation. The pit stops were well stocked and the crew friendly and helpful across the entire course. I’d recommend this event. Paul

So well organised! Given everything going on it was absolutely brilliant. The aid stations were so well supported and the volunteers were so supportive and attentive. The views were spectacular and well worth the difficult hills. Charly

Amazing race. So well run, the volunteers are fabulous and the pit stops extremely well stocked. Highly recommended. Sarah H

My first ultra, the whole thing from start to finish was phenomenal, what really stodd out was how lovely the support staff were, cheering us on and their words of encouragement were so lovely! Kylie B

Brilliant event! A great intro into ultra, as so well supported and signed. Stunning route. Felt like I had all the information I needed in the lead up and the pit stops and organisation on the day were seamless. Amie F

Reviews thanks to RaceCheck