The 180km three-loop bike course represents one of the toughest iron-distance routes on offer in the UK, with around 2,800m of ascent covering ‘areas of outstanding beauty’ in the High Weald area of Kent, before passing through Hartfield and over the Ashdown Forest.

The marathon covers a four lap run route mainly an off road trail run, circumnavigating the two stunning estates of Hever Castle and Chiddingstone Castle before an iconic finish in front of the Hever Castle drawbridge that once gave passage to King Henry VIII.

An amazing, unforgettable experience

Athletes are treated to an amazing event village to top off the whole experience, with live bands playing throughout the day, a climbing wall, archery, catering, bike support and more. You’ll cross the finish line in front of Hever Castle with a medal, T-shirt and memories that will last a lifetime.

Last year’s event was won by pro triathletes Darren Jenkins and Bethan Fowler, whilst behind them came hundreds of amateur triathletes with their own stories of courage and endeavour. Amongst them was Anthony Gerundini, who was completing his 100th iron-distance triathlon, whilst many had chosen The Bastion as their first time at attempting what many consider the ‘toughest one-day physical challenge’ in the world – drawn by the amazing athlete support and welcoming atmosphere present at all Castle Triathlon Series races.