The Bastion | Full iron distance | Castle Triathlon Series | Castle Triathlon Series


The Bastion - Full iron distance

The iconic endurance challenge kicks off with a 3.8km lake swim before a 180km looped bike course around the Kent countryside. A 42km marathon run completes what is ‘one of life’s defining races’.

Read more:

The Bastion - Full iron distance

Hever Castle, Kent

The Bastion full iron-distance triathlon will be back, for the sixth time, on 4th July 2021.

A nurtured and exclusive field continues to show loyalty and the gritty determination needed to get round the hardest of our challenges.  We look forward to welcoming them and to new competitors ready to push themselves to their limits of endurance.

Bastion Hever Castle Triathlon Long Distance Half Iron

About The Bastion

Set within close proximity to London and triathlon’s heartland of the south-east, each leg of The Bastion has been carefully designed to offer the ultimate challenge for both newcomers to long-distance triathlon and experienced long-course hands.

The Bastion, the final stronghold of a medieval castle, features a 3.8km river and lake swim, a true toughie of a 180km bike course with 3,000m of climbing and a 42.2km run course that takes place largely off-road including running through the grounds of the beautiful Chiddingstone Castle. The event has generated rave reviews, helping grow this event into one of the truly iconic long distance triathlons in the world.

220 Triathlon has listed The Bastion as a ‘must-do’ race.

The event scores 4.8/5 on RaceCheck. See reviews here. 

Get a taster of The Bastion course

Course Maps

Please take a moment to study these in details.

The Bastion is an exciting and busy event with lots of different courses taking place throughout the day. There will be a full brief the day before your race 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.

Results and photography

Find the Races Results from previous years here along with amazing shots of participant’s photography during the event.

If you have any queries please contact Stuweb Timing Solutions here.

I will be entering the Gauntlet at Hever shortly and Bastion again for 2015. The events, although tough, are excellent and much better than the IM branded ones. Thanks again.
Dave Bowden
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.

Find out more


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.

Find out more

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!

Find out more


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)

Find out more