- Sat 18 Jul 2026
- Early bird
Early bird on now
08:00
Age 18 & over on 31 Dec 2026
£260-£290
- 1.2 miles lake swimming
- 66 miles road cycling + 3300 ft ascent
- 14 miles trail running + 1300 ft ascent
Event overview
A unique journey from castle to coast.
Begin with a calm 1.2-mile lake swim, then ride 67 miles through the rolling Surrey Hills before a 14-mile trail run across the South Downs, finishing on Brighton seafront.
This isn’t the fastest route from A to B — it’s the most rewarding. Winding through the North and South Downs, you’ll conquer climbs, soak up sweeping views over London and Brighton, and enjoy every mile knowing you’re part of something special.
Designed to be experienced rather than raced, Castle to Coast is a sportive triathlon — a fully supported, non-competitive adventure open to all. Relaxed cut-offs, flexible starts, and the freedom to complete the course alongside friends or clubmates make it a truly social triathlon experience.
Every detail is taken care of, from bag transport and finish-line meals to course signage, medical support and mechanics. All you need to do is swim, bike, run — and enjoy the unforgettable journey from Windsor Castle to Brighton.
Highlights
Logistics
From making sure your bags are available to you at every stop on the journey to delivering your finish line meal, the crew is here to take care of all the logistics.
On course support
The event is fully supported from the thousands of arrows out on course, to the mechanics and medical teams. We have a professional team of experienced route managers who make sure you have everything you need on event day.
Volunteers
Every year, the Tri community comes together to support the event and help athletes - be it their first or hundredth triathlon - get the most out of the event.
Event photos
Event video
- Average fitness
- Event village
- Hybrid bike
- Newcomers
- Road bike
- Teams
Team option
Divide and conquer.
The team option is in part self-supported so you’ll need 2 or 3 team members and a car in order to make it happen.
Your swimmer will start the event by completing their 1.2-mile swim. On exiting the water, they will come into the transition village and pass the timing chip to the second team member, who will go out on the bike. Your team will then be responsible for transporting your runner (and swimmer) from Windsor down to Hassock,s ready to start the run.
After your runner has departed, you’ll collect your bike and load it into the car. The swimmer and cyclist will then make their way down to Brighton Seafront, ready to run down the finish chute together, collecting their medals and finish line goodies on the way.
- Bone conducting headphones only
- Cut off time
- Distance markers
- First aid
- Food stations
- Marshals
- Point to point
- Return transport
- Water stations
- GPX available
GPX route
The route is displayed on the map above.
Cut offs
- The Swim will need to be completed within 1hr 20min of the event start
- The Bike will need to be completed within 7.5hrs of the event start
- The Run will need to be completed within 11.5hrs of the event start
Map
Swim

Inland open water swim
The swim and transition 1 is held at the wonderful Eton Dorney rowing centre.
Your swim begins with a rolling start, from a short countdown we start to let swimmers into the water to begin their swim. We then allow people to start for up to 20 minutes after this the start time, this means you can go off with the faster initial rush or chill out and take your time.
Once you’re out of the water, it's a short stroll to transition to get ready for the bike.
Bike

Open road/country lanes
The bike portion of the event departs Dorney and heads round the outskirts of Windsor with views of Windsor Castle. We stick to open roads through Berkshire, Surrey and Sussex to the foot of Ditchling Beacon. The route has been designed to make the most of both the stunning scenery and challenging climbs found in the Surrey Hills Area of Outstanding Natural Beauty.
Aid stations, toilets and mechanical support are provided along the route. This relaxed sportive takes place on open roads; therefore participants must obey the rules of the road.
Run

90% trail / 10% road
Hassocks Sports Centre is home to Transition 2. You’ll drop off your bike and collect your running kit. You have full use of the leisure centre facilities so you can take your time and make sure your ready for what comes next, some people have even been known to grab a quick shower.
To finish the event off, we’ve got a fantastically scenic run heading from Hassocks over Ditchling Beacon and down to the seafront at Brighton, where your day out will finish.
The run route has a challenging start, taking you up onto the South Downs Way, along Ditchling Beacon and provides epic views over the surrounding countryside. You will then slowly descend through the countryside all the way down to the seafront. The run is around 80% trail and 20% tarmac.
The finish
What better place to finish your day than in the heart of Brighton at Hove Lawns, right on the seafront. You’ll be right in the heart of Brighton next to the i360 tower and the Angel of Peace statue.
Once you're through the finish line, you can make your way down to the sea and take a dip, enjoy some post-event food and drink and then either catch a coach back to the start or make a night of it in Brighton.
- Bag transfer
- Rural
Event HQ
Dorney Lake
Off Court Lane, Lake End Road
Windsor
Buckinghamshire
SL4 6FJ
UK
- Chip timing
- Goody bag
- Map
- Medal
Included
- GPX downloads
- Chip timing
- Online tracking
- Bag transfer
- Professional bike transportation (fully insured)
- Mechanical crews on the bike course
- Medal
Optional extra
Need a lift home?
- Return transport tickets will be available to book

What an awesome experience. Brutal and beautiful in equal measure. I still cannot quite believe I did it, the furthest distance and the most challenging event I have taken part in. Well organised, great pit stops, helpful marshals, well marked course, and lovely finishing area. Brilliant double-sided medal. Would highly recommend for anyone wanting to do something a bit different.
The swim was in an iconic Olympic location and the ride took us through the undulating Surrey Hills through some great scenery and beautiful villages. The run was brutal, however the fantastic countryside and views with minimal tarmac and urban setting, kept you going.
What an amazing event! Brilliantly marshalled, well stocked feed stations and incredibly well organised from start to finish. This was my first triathlon and despite a couple of mishaps of our own making, we couldn’t have enjoyed it more! Matt C
The marking out of the cycle and run courses was very good. No need for navigational aids (fortunately). The swim was lovely. Very well organized throughout. I'll be back next year! Mark E
I love this event. I have done it twice now and marshalled it the year in between. It is so chilled, but gives you valuable experience for packing different coloured bags, transitions and dealing with longer distances. I'll be back for more in 2025. Kate S
What an outstanding event. I always consider carefully where I'm going to be spending my money and on which events... I'll be signing up for next year. Spectacular route, amazing volunteers and staff and incredible challenge. Relaxed transitions and great atmosphere throughout. The only flat bit is the swim, so get your bike training topped up. This event was my first triathlon and can recommend to anyone thinking they fancy dipping their toe into multi-discipline sport events without having to worry about the many rules and specific kit demands of a competitive triathlon. You won't regret investigating your time and hard earned money in Castle to Coast. Justin W
This was my first event of this type so I felt very nervous even tho I had trained I knew that I wouldn’t be as fast as the other people , but throughout the whole event everyone was really helpful and supportive we were all treated with kindness and encouragement. This was a difficult sportive for a beginner one not to be underestimated but I would highly recommend it to anyone . Thank you for a fantastic day . Rebecca O
For me a very tough event but brilliantly arranged, managed and supported! Stewart H
This is a fantastic event for anyone who is looking for a challenge. Choose to do it solo or in a relay, this event has something for everyone. The course is fantastic and takes in the beautiful countryside from Windsor to Brighton. The organisation is superb, all you need to do is bring the grit and determination. Definitely a great day! Carol M
Drawn to the idea of a sportive style middle distance triathlon without the strict cut offs for each discipline. Great friendly event. Loved the relaxed feel and atmosphere. Very well organised and excellent communications in the lead up to the event. Michyla C
Reviews thanks to RaceCheck
- Age 18 & over on 31 Dec 2026
- Entries open
- Enter online
Entry fees
Early bird entry fee
£260.00
Team entry fee
£290.00