The Series

The Festival of Endurance

Sunday 4th July 2021 promises another exhilarating and atmospheric celebration of ‘going long’ at the iconic and stunning Hever Castle. Loved by competitors and spectators alike the event is hailed the most friendliest and beautiful on the tri radar.

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The Festival of Endurance

Sunday 4th July 2021

We are pleased to announce that the Festival of Endurance will return on Sunday 4th July 2021.

Due to popular demand the Gauntlet half iron distance triathlon is returning with athletes racing alongside the full iron distance Bastion competitors around much of the same course.  Whilst these two epic triathlons are taking place a further 6 sets of endurance challenge races are taking place including Aquabike, Aquathlon, Duarhtlon, Long Distance Running and Long Distance Swimming making this a true celebration of the art of “going long”.  Please read on for more details.

2020 Cancellation Notice


With a very heavy heart we had to take the difficult decision to cancel the 2020 Festival of Endurance event at Hever Castle on the 5th of July.  Although hugely disappointing, we know that you, like us, understand that the safety of society at large and of each other is paramount at this time.  Read see the read the official statement here

To all those registered for this event, please use the button below to see Next Steps.

The Bastion

3.8km/180.2km/42.2km – Full iron distance race.

Set in close proximity to London and in the heartland of Henry VIII’s old hunting grounds, each leg of the Bastion has been designed to offer the ultimate physical challenge to athletes but in the most beautiful setting. The Bastion, which were the final strongholds of medieval castles, features an iridescent 3.8km river and ornamental lake swim, a true toughie of 180km bike course with 2,700m of climbing and a 42.2km trail run that takes place largely off road and incorporates the gardens of both Hever and Chiddingstone Castles. You won’t get a personal best over this distance but you will have the bragging rights to arguably one of the toughest and most iconic races of its kind anywhere in the world.

Triathlon England National Middle Distance Triathlon Championship

4th July 2021

1.9km/90km/21km – Half iron distance race.

The Festival of Endurance at Hever Castle will host the Triathlon England Middle Distance Triathlon National Championship. Want to become an English Champion? Make sure you’re eligible here.  We have been re-awarded the English Middle Distance Championships which are due to take place on the same calendar weekend, Sunday 4 July. 2021.

This middle distance course is made for a National Championship with the 1.9km swim will involve a single loop taking in the main Hever Castle lake and a tributary of the river Eden.  The 90km cycle (2 loop course) winds its way through the stunning High Weald of Kent and the Ashdown Forest.

Click here for cycle elevation route
Click here for run elevation route

The 21km run course is 2 loops of 10.5km, will take in the existing 5km Hever Castle Triathlon course but with a 5km extension via tracks and bridle paths though the historic local village of Chiddingstone. The course includes a strong off road element which allows a highly inspirational setting often praised and welcomed by the elite triathletes.

The Gauntlet

1.9km/90km/21.1km – Half iron distance race.

The half iron distance equivalent of the Bastion, we call the Gauntlet, previously British Middle Distance Championships event and filmed by Channel 4.  Again no chance of a PB on this super-tough course but you will have undertaken a huge challenge of one of Europe’s most beautiful races.

Long course training distances

We are offering you the chance to swim, bike or run sections of The Bastion, arguably the most grueling Full Iron distance course on the planet. Fully timed and fully supported just like those taking on the iron-distance race alongside you.

The perfect training ground to prepare for any iron-distance challenge or to get an idea of what might await you next year should you return for the ultimate Castle Triathlon Series challenge and take on The Bastion. This is a fantastic training race set in a stunning location in mid-summer, perfect for those taking on an iron-distance in the second half of the year.

The Aquabike Challenge


  • 1.9k swim: 60k cycle: 4k optional run (Laps 1:1:1)
  • 3.8k swim: 120k cycle: 4k optional run (Laps 2:2:1)

There’s a training option for everybody who’s into long distance.  After the unique swim you’ll head out on the fully marshalled and signed bike course with supported feed stations. This circular cycle route will take competitors out of Hever Castle, up through the High Weald of Kent before passing through and over the Ashdown Forest and into the village of Maresfield.  After a quick tour of the village competitors retrace their steps to the top of the forest before returning to Hever via the historic and quintessentially English villages of Groombridge, Fordcombe and Penshurst.  Finishers have the option of finishing with a gentle 4K run that circumnavigates the lake and stunning grounds of the Hever estate.

The Aquathlon Challenge


  • 1.9k swim / 10k run (Laps 1:1)
  • 3.8k swim / 21k run (Laps 2:2)

After the unique swim (1 or 2 loops), competitors will then embark on the 10k/21km run course, which follows largely off road tracks and bridle paths between Hever Castle, through the historic local village of Chiddingstone, before finishing right in front of the Castle.

The Duathlon Challenge


10.5k / 45k / 4k (Laps 1:1:1)
21k / 90k / 10.5k (Laps 2:2:1)

After a unique run (1 or 2 laps) through the glorious Kent countryside and around the private estates of Hever and Chiddingstone Castles, cycle up to the highpoint of the Ashdown Forest (1 or 2 laps) before finishing off with further laps of the beautifully manicured gardens and local network of paths and trails.

The Hever Marathon

26.2 miles/ 42.2k

After the huge success of the inaugural event in the 2018 Series, the marathon returns to the atmospheric Festival of Endurance at Hever Castle.

Forget the city marathon, and fill your lungs with country air and stunning scenery before you conquer your marathon by a castle drawbridge. This new marathon, promises the most stunning off road course in the UK, a truly motivational and beautiful route that will distract you from the challenge itself. The four-laps take in two castles, two lakes, quaint Kentish villages, oast houses and with spectators and locals cheering you on all the way!

Marathon Pacer Timings : 4.00hrs, 4.30hrs, 5.00hrs, 5.30hrs (this is slower paced course than many road ones –  4.30hrs on this course is equivalent to a 4.00hrs on a road course!)

The Hever Half Marathon

13.1 miles/ 21.1k

Take on the half marathon at our 2019 Festival of Endurance, on the most stunning off road course in the UK.

Starting at the drawbridge of the Hever Castle, this two-lap course takes in two castles, two lakes, quaint Kentish villages, oast houses with spectators and locals cheering you on all the way! Finish your race with a big celebration, medal and finishing line banquet in sight of the castle.

Half Marathon Pacer Timings : 1.45hrs, 2.00hrs, 2.15hrs, 2.30hrs

The Hever Long Distance Swim


  • 1.9k circuit
  • 3.8k circuit
  • 10K Marathon Swim (NEW in 2018) Entry tickets available to Individuals and Relay team of 5 (each team member takes on the 2k loop circuit).

The swim course leaves from the Italianate loggia taking competitors down the length of the main lake and heading into the scenic river section.This tributary of the River Eden wraps around 16 Acre Island allowing spectators to watch and cheer competitors on from only a few meters away. The Speedo team will be on hand to welcome you at the finish, then it’s time to relax and enjoy a complimentary bacon roll back at the Event Village.

Distances, Timings, Pricing

Sunday 4th July 2021

Race Name
Race Distance
Race Price
(Individual / Relay)
Start time
The Bastion Full Iron Distance
3.8km / 180km / 42.2km
£360 / 450
Swim Marathon
10K Swim
£80 / 135
The Gauntlet Half Iron Distance
1.9km / 90km / 21km
£220 / 270
Long Distance Aquabike (Swim / Bike)
3.8km swim / 120km bike
Middle Distance Aquabike (Swim / Bike)
1.9km swim / 60km bike (optional 4km run)
*Long Distance Aquathlon (Swim / Run)
3.8km swim / 21km run
Middle Distance Aquathlon (Swim / Run)
1.9km swim / 10.5km run
Long Distance Swim
3.8km swim
Middle Distance Swim
1.9km swim
Long Distance Duathlon (Run / Bike / Run)
21km / 90km / 10.5km
Middle Distance Duathlon (Run / Bike / Run)
10.5km / 45km / 4km
Full Marathon
42.2km run
Half Marathon
21.1km run

Start times are approximate and shown here as a general guide. These are subject to change. Each distance start time is preceded by a brief by the Race Director.

Relay options apply for 10K Swim, Gauntlet and Bastion competitors.

Entrants will be notified via email with full race details, including confirmation of wave times, 2 weeks prior to the event.

*The Long Distance Aquabike includes an optional 4km run.

Race day information

Two weeks prior to event, this section will give you everything you need to know about race day, including wave times, registration opening details, spectator entry, camping info and water temperature readings etc.

Course maps

Please take a moment to study these in details.

The Festival of Endurance at Hever Castle is an exciting and busy event with lots of different courses taking place throughout the day. There will be a full brief before your race start but it’s a good idea to familiarise yourself with the course and in particular any key junctions to ensure you take the correct route.

2019 Results and photography

Congratulations to everyone who took part in the 2019 festival of sport.  We hope to see you again in 2020!

Use the buttons below to find  Races Results along with amazing shots of participant’s photography during the event.

Useful information

Race licence

The Castle Triathlon Series UK events are governed by the British Triathlon Federation and their technical officials will provide guidance on the day and in the run up to the event.

On race day, all participants involved in a multi-discipline sport are required to produce a valid triathlon governing body membership card or purchase a Day Licence. The Day Licence fee is £5 Adult £1 Child and can be purchased at Registration on event day.  More information here

Spectator Offering

The spectator experience at the Castle Triathlon Series has become almost as famous as the spectacular backdrops and classic courses, and has made passing time before your loved ones finish the race a thing of the past.

Competitor Photography

PRE-Race day offer! AWOL Adventure photography team will be positioned around the course, finish line, and event village ready to capture that timeless photo – Just don’t forget to SMILE!

Pre-order your digital bundle of pictures for a special HALF PRICE DISCOUNT. Here’s how it works…..

ALL your Digital Photos for for half price
Min. 2 photos GUARANTEED or your money back*
Bundle goes to full price after the event so hurry!

*Click here for quick FAQ and details of Awol Adventure guarantee

Rules and Terms and Conditions

Please read and understand the general rules, in particular the cut-off times, before competing to ensure a fantastic race for you and everyone else.

Travel, accommodation and directions to the venue

Click the link below to find out everything you need to know about all of our venues.

Water quality

Please see the latest water quality tests for Hever Castle lake. All tests are undertaken using the EU Water Bathing Directive as the benchmark.

Water temperature

For swim length up to 1500m wetsuits will be optional on race day if the temp remains between 14 and 22 degrees centigrade and over 1500m swim length wetsuits will be options between 15 and 23 degrees centigrade.

Race distances

Race distances

For the absolute beginners and children to the professional triathletes, the Castle Triathlon Series offers a wealth of race distances to suit all levels.

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Hosted at a selection of stunning and iconic castles across the UK, Ireland and France, the Castle Triathlon Series events all promise an inspirational and memorable race experience.

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Take part

We pride ourselves on offering a bespoke and tailored offering for all those wishing to take part; from first timers, old timers, juniors, female focus, elites, tri clubs, corporates, there’s a race for everyone!

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Trade your time for a free race place! We offer a Volunteer Scheme, whereby a free race is given in return for a day’s marshalling at any one of the Castle Triathlon Series events. (terms apply)

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