Ironman triathlons in the UK
An Ironman or full distance triathlon is one of the toughest event formats around and only do-able by the most committed athletes with both the physical and mental endurance to cross the finish line. Also called a 140.6 triathlon or full distance triathlon, these long-distance events involve a 2.4-mile swim (3.9km), a 112-mile bike ride (180km), and a 26.2-mile run (42.2km) - a total of 140.6 miles completed in an average of around 10-15 hours. Select your location for full distance triathlons in your area or scroll down to see major events coming up.
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Full distance triathlons in 2025
Featured events are listed below - select a month/region or the map view to see all events.

- Sun 8 Jun
- €375
Chateau de Chantilly | Bastion Triathlon
Race through the beautiful grounds and surrounding area of the stunning Château de Chantilly in The Bastion Iron Triathlon XXL then celebrate with friends and family in the festival village.
- 3.8 km lake swimming
- 180.2 km road cycling
- 42.2 km road running

- Sat 5 Jul
- £275-£295
ATW Odyssey Full Distance Triathlon
Complete your own Odyssey on a journey of self-discovery in the Cambridgeshire countryside featuring a swim in the River Ouse, a scenic ride and a run around the beautiful town of St Neots.
- 3800 m river swimming
- 180 km road cycling
- 42.2 km road running

- Sun 31 Aug
- £250
Roadford Lake Triathlon | Iron Distance
Brand new to the popular Roadford Lake Tri, the Iron Tri has a superb swimming venue with quiet rolling roads for the bike course and a cracking run too. Plus there's lakeside camping available too.
- 3.8 km lake swimming
- 185 km road cycling
- 42 km road running
Ironman triathlons near you
Select your location for Ironman and 140.6 triathlons in your area.