United Kingdom
IRONMAN in the UK: which race to choose
5 IRONMAN races in the UK in the catalogue: 2 full distances and 3 IRONMAN 70.3. Bike climbing, the swim and the month separate them.
Where the figures come from
Counts, climbing, water averages and cut-offs are read from the catalogue and recalculated whenever a race is updated. They come from the race pages of ironman.com and from the organisers' sites for Lakesman, Hever Castle and Celtman. The race-day water readings quoted come from the "Historical weather" table of the ironman.com course pages, for 2024 to 2026.
The United Kingdom page lists every race in the country. For the rest of the continent, see IRONMAN in Europe and half-distance triathlons in Europe.
Every triathlon in the UK
Add a month or a distance to narrow the list.
- IRONMAN 70.3 Bolton
Bolton, United Kingdom
- Date
- 6 Jun 2027
- Distance
- Middle
- Circuit
- IRONMAN
- Water
- 19 °C
- Bike
- Rolling
- Run
- Rolling
- Entries
- Sold out
- CELTMAN! Extreme Scottish Triathlon
Shieldaig, United Kingdom
- Date
- 12 Jun 2027
- Distance
- Full, extreme
- Circuit
- XTRI
- Water
- n/a
- Bike
- Hilly
- Run
- Hilly
- Entries
- Open
- Royal Windsor Triathlon – Olympic
Windsor, United Kingdom
- Date
- 13 Jun 2027
- Distance
- Olympic
- Circuit
- Independent
- Water
- n/a
- Bike
- n/a
- Run
- n/a
- Entries
- CELTMAN! XTRI Solo Point Five
Shieldaig, United Kingdom
- Date
- 19 Jun 2027
- Distance
- Middle, extreme
- Circuit
- XTRI
- Water
- 15 °C
- Bike
- Hilly
- Run
- n/a
- Entries
- Open
- Lakesman Full
Keswick, United Kingdom
- Date
- 20 Jun 2027
- Distance
- Full
- Circuit
- Independent
- Water
- n/a
- Bike
- n/a
- Run
- n/a
- Entries
- Open
- IRONMAN 70.3 Swansea
Swansea Bay, United Kingdom
- Date
- 11 Jul 2027
- Distance
- Middle
- Circuit
- IRONMAN
- Water
- 16 °C
- Bike
- Hilly
- Run
- Flat
- Entries
- Sold out
- IRONMAN Leeds
Leeds, United Kingdom
- Date
- 15 Aug 2027
- Distance
- Full
- Circuit
- IRONMAN
- Water
- 21 °C
- Bike
- Hilly
- Run
- Hilly
- Entries
- Open
- London T100
London, United Kingdom
- Date
- 22 Aug 2027
- Distance
- 100 km
- Circuit
- T100
- Water
- n/a
- Bike
- Flat
- Run
- Flat
- Entries
- Open
- Supertri Brighton – Olympic
Hove, United Kingdom
- Date
- 29 Aug 2027
- Distance
- Olympic
- Circuit
- Independent
- Water
- n/a
- Bike
- Flat
- Run
- Flat
- Entries
- Open
- IRONMAN 70.3 Weymouth
Weymouth, United Kingdom
- Date
- 12 Sept 2027
- Distance
- Middle
- Circuit
- IRONMAN
- Water
- 17 °C
- Bike
- Rolling
- Run
- Flat
- Entries
- Sold out
- IRONMAN Wales
Pembrokeshire, United Kingdom
- Date
- 19 Sept 2027
- Distance
- Full
- Circuit
- IRONMAN
- Water
- 17 °C
- Bike
- Hilly
- Run
- Hilly
- Entries
- Sold out
- Hever Castle Triathlon The Gauntlet Middle Distance
Hever, United Kingdom
- Date
- 26 Sept 2027
- Distance
- Middle
- Circuit
- Independent
- Water
- n/a
- Bike
- Hilly
- Run
- Rolling
- Entries
- Open
Full distances: Leeds in August, Wales in September
IRONMAN Leeds was first held in 2025. The swim is two laps of Waterloo Lake in Roundhay Park. The bike rides out to Shadwell, then covers three 55 km loops north of the city, past Harewood House and Eccup Reservoir. Its main climb is Black Hill Road, used on stage 4 of the 2018 Tour de Yorkshire. Total climbing: 2574 m. The run is four 10 km loops in and around the park, with 439 m of climbing. ironman.com measured the lake at 21 °C in 2025.
IRONMAN Wales has been held in Pembrokeshire since 2011. The sea swim starts from North Beach in Tenby, in two laps, and a 1 km run up a zigzag ramp leads to transition. The bike covers two loops of the Pembrokeshire Coast National Park. The run is four loops through Tenby, past the medieval town walls. The catalogue does not yet publish climbing figures for this course. The sea was measured at 17 °C in 2024 and 2025. Leeds and Wales both allow 17 h.
June in Bolton: a lake swim and a finish at the town hall
IRONMAN 70.3 Bolton opens the British IRONMAN season in June. The swim is one lap of Pennington Flash. Transitions are split: T1 is by the lake, T2 in Queens Park, in Bolton. The bike starts with two loops through Lowton, Abram and Bickershaw, then two loops of Horwich and Bolton along Chorley New Road. ironman.com says these roads will be familiar to those who raced the former IRONMAN UK. The course has 840 m of climbing, the least of the British 70.3, and ironman.com rates both bike and run rolling.
The run is two loops of the town centre and Queen's Park, with the finish in front of Bolton Town Hall. The lake was measured at 17 °C in 2025 and 18 °C in 2026.
Sea swims: Swansea in July, Weymouth in September
IRONMAN 70.3 Swansea swims one lap from the Prince of Wales Dock. A 500 m run leads to transition in East Burrows car park, and an optional bag holds shoes for it. The bike, 1.5 loops, goes through Mumbles and along the Gower clifftops, then inland and back along Swansea Bay: 1062 m of climbing, the most of the British 70.3. The run is two flat loops from the city centre towards Mumbles. ironman.com gives an average water temperature of 16 °C; it measured 18 °C in 2024 and 24 °C in 2025.
IRONMAN 70.3 Weymouth swims one L-shaped lap from Weymouth beach. The bike is a single loop through the Dorset countryside, north to King's Stag and back through Dorchester, rated rolling by ironman.com. The run, 2.5 laps, is flat, along the seafront and Custom House Quay. The sea was measured at 17 °C in 2024 and 2025. The race falls one week before IRONMAN Wales.
Outside IRONMAN: Keswick, Hever and the Highlands
Lakesman Full is a full distance in Keswick, in June, with the swim in Derwentwater. On 27 October 2026 its site listed an early entry at £420, secured with a £75 deposit. The organiser publishes its cut-offs in the athlete guide.
Hever Castle Triathlon The Gauntlet Middle Distance, in September in Kent, starts in waves. Its bike has 1460 m of climbing and is rated hilly. The organiser lists the entry from £245.
London T100, in August, has an amateur race over the professional distance, 2 km, 80 km and 18 km. In the Highlands, Celtman is an extreme triathlon; the extreme triathlon guide covers it.
Bolton, Swansea and Weymouth on the same rows
Month, water, climbing and cut-off, side by side.
IRONMAN 70.3 Bolton
IRONMAN 70.3 Swansea
IRONMAN 70.3 Weymouth
- Race 1 IRONMAN 70.3 Bolton
- Race 2 IRONMAN 70.3 Swansea
- Race 3 IRONMAN 70.3 Weymouth
- Circuit
- IRONMANIRONMANIRONMAN
- Distance
- Middle distanceMiddle distanceMiddle distance
- Terrain
- RoadRoadRoad
- Swim
- 1.9 km1.9 km1.9 km
- Bike
- 90 km90 km90 km
- Run
- 21.1 km21.1 km21.1 km
- Date
- 6 Jun 202711 Jul 202712 Sept 2027
- Country
- United KingdomUnited KingdomUnited Kingdom
- Registration
- Sold outSold outSold out
- Swim venue
- LakeHarbourSea
- Average water temperature
- 19 °C16 °C17 °C
- High air temperature
- 16 °C24 °C19 °C
- Low air temperature
- 9 °C12 °C7 °C
- Bike profile
- RollingHillyRolling
- Bike elevation gain
- 840 m1,062 m1,043 m
- Run profile
- RollingFlatFlat
- Run elevation gain
- 214 m13 mn/a
- Overall cut-off
- 8 h 30 min8 h 30 min8 h 30 min
- Altitude
- 105 m18 mn/a
- First edition
- 202120222016
- Swim start
- Rolling startRolling startRolling start
- Entry fee, from
- £360£360n/a
What the averages leave out
On 27 October 2026, ironman.com showed general entry sold out for 2027 at IRONMAN Wales, IRONMAN 70.3 Bolton, IRONMAN 70.3 Swansea and IRONMAN 70.3 Weymouth. IRONMAN Leeds was open. Prices are in pounds, and the Leeds entry page shows a price that includes processing fees and VAT. Registration is always done on the organiser's site.
Under the 2026 IRONMAN Competition Rules, age-group athletes may wear a wetsuit up to 24.5 °C and must wear one below 16 °C. The limit for professionals is 21.9 °C. The race-day readings quoted on this page run from 17 to 24 °C, and the decision is made on race morning. The wetsuit rules guide sets out every threshold.
Questions
How many IRONMAN races are there in the UK?
There are 5: 3 IRONMAN 70.3, in Bolton, Swansea and Weymouth, and 2 full distances, in Leeds and Pembrokeshire. The catalogue lists 12 triathlons in the UK in all.
Is IRONMAN UK still held in Bolton?
Bolton now hosts IRONMAN 70.3 Bolton, a half distance, in June. ironman.com says its bike course uses roads familiar from the former IRONMAN UK. For a full distance: IRONMAN Leeds, IRONMAN Wales.
Which IRONMAN in the UK is the hardest?
The catalogue gives IRONMAN Leeds 2574 m of bike climbing over 180 km and 439 m on the run. It has no climbing figures for IRONMAN Wales yet, so the two courses cannot be compared on this measure. Leeds and Wales both allow 17 h. The hardest IRONMAN courses page ranks courses worldwide.
Which 70.3 in the UK is the flattest?
IRONMAN 70.3 Bolton, with 840 m of bike climbing. The runs at Swansea and Weymouth are rated flat. The easiest 70.3 races page compares courses worldwide.
When is the triathlon season in the UK?
From June to September in the catalogue. Among them: Bolton, Lakesman and Celtman in June, Swansea in July, Leeds and London T100 in August, Weymouth, Wales and Hever in September.
Do I need a wetsuit for an IRONMAN in the UK?
Below 16 °C a wetsuit is compulsory for age-group athletes under the 2026 IRONMAN rules, and it is allowed up to 24.5 °C. The race-day readings at the British IRONMAN races ran from 17 to 24 °C between 2024 and 2026. The decision is made on race morning.
Pick the month, then the race
Open the finder on races in the UK, or answer a few questions to get a shortlist.