Half Ironman triathlons

Half Ironman triathlons

Middle distance (aka 70.3) triathlon events | 1.2 mile swim + 56 mile bike + 13.1 mile run

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Half Ironman triathlons in the UK

Completing a Half Ironman is a real feat of endurance but is do-able if you are willing to put in the training time. Also called a 70.3 triathlon or middle distance triathlon, these long-distance events involve a 1.2-mile swim (1.9km), a 56-mile bike ride (90km), and a 13.1-mile run (21.1km) - a total of 70.3 miles completed in an average of around 6 hours. Select your location for 70.3 triathlons in your area or scroll down to see major events coming up.

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70.3 triathlons in 2025

Featured events are listed below - select a month/region or the map view to see all events.

Swim, bike, run your way from Windsor Castle to Brighton on this unique, non-competitive, point-to-point adventure through the North & South Downs. Fully way-marked (no navigation) and full support.
  • Sat 19 Jul
  • £265-£295
Windsor, Buckinghamshire, UK

Castle To Coast Triathlon

Swim, bike, run your way from Windsor Castle to Brighton on this unique, non-competitive, point-to-point adventure through the North & South Downs. Fully way-marked (no navigation) and full support.

  • 1.2 miles lake swimming
  • 67 miles road cycling + 3550 ft ascent
  • 14 miles trail running + 1512 ft ascent
A jewel in the castle crown! Get active in the beautiful grounds and surrounding area of stunning Leicestershire in the epic Gauntlet Triathlon! Celebrate in the festival village afterwards.
  • Sun 20 Jul
  • £245-£295
Grantham, Leicestershire, UK

Belvoir Castle | Gauntlet Triathlon

A jewel in the castle crown! Get active in the beautiful grounds and surrounding area of stunning Leicestershire in the epic Gauntlet Triathlon! Celebrate in the festival village afterwards.

  • 1.9 km lake swimming
  • 90 km road cycling + 957 ft ascent
  • 21 km road running
Awarded the Event of the year (2021) in the Welsh Triathlon Awards, The Craft Snowman is well known as the toughest multi-terrain triathlon in the UK. It is not for the faint-hearted.
  • Sun 3 Aug
  • £224.99-£249.99
Betws-y-Coed, Clwyd, UK

Craft Snowman Legend (70.3) Triathlon

Awarded the Event of the year (2021) in the Welsh Triathlon Awards, The Craft Snowman is well known as the toughest multi-terrain triathlon in the UK. It is not for the faint-hearted.

  • 1900 m lake swimming
  • 95.6 km road cycling + 5045 ft ascent
  • 21.2 km multi terrain running + 2926 ft ascent
Now twice-yearly due to popularity, the 70.3 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.
  • Sun 31 Aug
  • £140
Lifton, Devon, UK

Roadford Lake Triathlon | Middle Distance

Now twice-yearly due to popularity, the 70.3 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.

  • 1.9 km lake swimming
  • 93 km road cycling + 4245 ft ascent
  • 21 km road running + 1073 ft ascent
Face up to the mountain in one of Europe's most inspiring locations. From Windermere to Coniston to summit England's highest mountain, if you love a tough and rewarding challenge - you'll thrive.
  • Sat 6 Sep
  • £240-£260
Ulverston, Cumbria, UK

THE ROC ENGLAND

Face up to the mountain in one of Europe's most inspiring locations. From Windermere to Coniston to summit England's highest mountain, if you love a tough and rewarding challenge - you'll thrive.

  • 1.5 km lake swimming
  • 92 km road cycling
  • 18.5 km multi terrain running
  • Recycling
  • Plastic bottle free
  • Music
  • Chip timing
  • Enter online
  • Mountainous
  • Event village
  • Rural
  • Mountains
  • Sustainability policy
  • Plastic-free event
  • Age 18 & over
  • Half Ironman (middle distance)
Bringing back the Sundowner 70.3 Triathlon! An unforgettable triathlon event at Allerthorpe Lakeland Park in Yorkshire is now back on the race calendar and 100% going ahead!
  • Sat 13 Sep
  • £120-£130
York, East Yorkshire, UK

Sundowner 70.3 Triathlon

Bringing back the Sundowner 70.3 Triathlon! An unforgettable triathlon event at Allerthorpe Lakeland Park in Yorkshire is now back on the race calendar and 100% going ahead!

  • 1900 m lake swimming
  • 90 km road cycling + 287 ft ascent
  • 21 km trail running + 17 ft ascent
The Big East and Maldon Triathlon is brought to you by the largest triathlon organiser in the UK! A great experience featuring a tidal river swim.
  • Sun 21 Sep
  • £160-£180
Maldon, Essex, UK

Big East Middle Distance Triathlon

The Big East and Maldon Triathlon is brought to you by the largest triathlon organiser in the UK! A great experience featuring a tidal river swim.

  • 1500 m river swimming
  • 86 km road cycling + 1112 ft ascent
  • 20 km trail running + 172 ft ascent
Not for the faint hearted, this race pushes competitors to their limits whilst visiting every corner of the beautiful castle estate and its surrounding rural area into the High Weald AONB.
  • Sun 28 Sep
  • £245-£295
Edenbridge, Kent, UK

Hever Castle | Gauntlet Triathlon

Not for the faint hearted, this race pushes competitors to their limits whilst visiting every corner of the beautiful castle estate and its surrounding rural area into the High Weald AONB.

  • 1.9 km lake swimming
  • 90 km road cycling + 2392 ft ascent
  • 21 km road running
THE ROC takes in the Highlands. Kinlochleven to the summit of Ben Nevis and back, including a Loch swim, stunning mountain/gravel bike sections and the UK's highest mountain!
  • Sat 4 Oct
  • £240-£260
Kinlochleven, Highland, UK

THE ROC SCOTLAND

THE ROC takes in the Highlands. Kinlochleven to the summit of Ben Nevis and back, including a Loch swim, stunning mountain/gravel bike sections and the UK's highest mountain!

  • 1.5 km lake swimming
  • 53 km mountain biking
  • 18.5 km multi terrain running
  • Recycling
  • Plastic bottle free
  • Music
  • Chip timing
  • Enter online
  • Hilly
  • Mountainous
  • Event village
  • Rural
  • Mountains
  • Sustainability policy
  • Plastic-free event
  • Age 18 & over
  • Half Ironman (middle distance)
The totally unique ROC format, from Abersoch Bay to the top of Wales’ highest mountain and back. Swim, Bike, Mountain, Bike, Run; THE ROC WALES is triathlon - tough and redefined.
  • Sat 9 May 2026
  • £195-£225
Pwllheli, Gwynedd, UK

THE ROC WALES

The totally unique ROC format, from Abersoch Bay to the top of Wales’ highest mountain and back. Swim, Bike, Mountain, Bike, Run; THE ROC WALES is triathlon - tough and redefined.

  • 1.5 km sea swimming
  • 100 km road cycling
  • 13 km multi terrain running + 3330 ft ascent
  • Recycling
  • Plastic bottle free
  • Entertainment
  • Music
  • Chip timing
  • Enter online
  • Hilly
  • Mountainous
  • Event village
  • Event expo
  • Coast
  • Mountains
  • Sustainability policy
  • Plastic-free event
  • Age 18 & over
  • Half Ironman (middle distance)
A lake swim, a trail run and a road ride over the course of the festival weekend. Conquer a triathlon challenge over two days. Includes Full Weekend Festival Ticket in the price!
  • Sat 16 - Sun 17 May 2026
  • £160-£165
Keswick, Cumbria, UK

Keswick Mountain Festival | Keswick Conqueror

A lake swim, a trail run and a road ride over the course of the festival weekend. Conquer a triathlon challenge over two days. Includes Full Weekend Festival Ticket in the price!

  • 3.6 km lake swimming
  • 100 km road cycling + 1625 m ascent
  • 25 km trail running + 866 m ascent
This triathlon returns for another successful year! It’s a superb swimming venue with quiet rolling roads for the bike course and a cracking run too. Plus there's lakeside camping available too.
  • Sun 17 May 2026
  • £135
Lifton, Devon, UK

Roadford Lake Triathlon | Middle Distance

This triathlon returns for another successful year! It’s a superb swimming venue with quiet rolling roads for the bike course and a cracking run too. Plus there's lakeside camping available too.

  • 1.9 m lake swimming
  • 93 km road cycling + 8490 ft ascent
  • 20 km road running + 3288 ft ascent
Challenge yourself to tackle a 100km Centurion this year, a distance made popular by the PTO race series. Ideal if you're training for a 70.3 Half-Iron or taking a step up from Standard Distance Tri.
  • Sun 24 May 2026
  • £120-£135
Bedford, Bedfordshire, UK

ATW Box End Centurion 100km Triathlon

Challenge yourself to tackle a 100km Centurion this year, a distance made popular by the PTO race series. Ideal if you're training for a 70.3 Half-Iron or taking a step up from Standard Distance Tri.

  • 2250 m lake swimming
  • 81 km road cycling + 1674 ft ascent
  • 20 km trail running + 340 ft ascent
Take on a superb middle distance triathlon at the fantastic Grafham Water. Suitable for all abilites, with a challenging, but achievable course, and custom medal at the finish line.
  • Sun 7 Jun 2026
  • £155-£175
Huntingdon, Cambridgeshire, UK

ATW Grafman Middle Distance Triathlon

Take on a superb middle distance triathlon at the fantastic Grafham Water. Suitable for all abilites, with a challenging, but achievable course, and custom medal at the finish line.

  • 1900 m lake swimming
  • 90 km road cycling + 1680 ft ascent
  • 21 km multi terrain running + 0 ft ascent

Half Ironman triathlons near you

Select your location for Half Ironman and 70.3 triathlons in your area.