IRONMAN 70.3 Boise
Boise, United States · July · IRONMAN
Why people love it
- Scenic Lucky Peak swim; a local pro called it among her most beautiful
- Flat shaded run on the Boise River Greenbelt to Julia Davis Park
- Fast start with a long dam descent, one rider reached 77 km (47.8 mi)/h (48 mph)
- Ice at every aid station and cooling tents
Watch out for
- Extreme heat: race-date highs of 34-41 °C (94-105 °F)
- The 2026 swim was cancelled, per an athlete report
- Swim shuttle leaves about 03:30 for a remote reservoir
- Wildfire smoke and storms have both been reported
- Few athlete reports since the race returned in 2025
Race
How racers feel about it, how well it is run, and how it treats a first timer. Counts for 27% of the overall score.
- Racer satisfactionLoved3.7
A 2026 reviewer rated it 4 out of 5 and loved the run. The 2026 swim was cancelled and few reviews exist. · Low confidence
- OrganizationWell run3.8
About 1,100 volunteers, ice at every aid station and cooling tents. The swim was cancelled in 2026 and described as a tough call. · Medium confidence
- First timer friendlyDoable2.9
Heat above 38 °C (100 °F), 579 m (1,900 ft) of bike climbing and a 03:30 shuttle make it a harder first half. · Low confidence
Course traits, not part of the score
- PR potentialAverage3.0
Fast dam descent and a flat shaded run, balanced by a rolling bike and heat. Sam Appleton won in 3:40 in 2025. · Low confidence
- Course easeTough2.7
Mid-hilly bike plus heat above 38 °C (100 °F). · Low confidence
Swim
Wetsuit odds, water temperature, calm, and the experience of the start. Counts for 15% of the overall score.
- Wetsuit legalUsually3.5
The reservoir was described as cold in 2025, so wetsuits are likely. Official legality was not confirmed. · Low confidence
- Water temperatureAcceptable3.0
Cold reservoir water was reported, with no temperature given. · Low confidence
- Calm waterSome chop3.2
The organiser says calm and clear, but one reviewer found the swim windy and challenging. · Medium confidence
- Swim easeEasy3.5
Point-to-point shuttle swim into Barclay Bay. Windy days add difficulty. · Low confidence
- Swim experienceGreat4.1
A local pro called it one of the most beautiful swims she has done. Clear reservoir among hills. · Low confidence
Bike
Road surface, closures, scenery and wind. Counts for 19% of the overall score.
- Road surfaceMixed3.3
Mix of rural and neighbourhood roads, with no complaints or praise found. · Low confidence
- Road closuresMostly closed3.9
Full and partial closures with heavy traffic control, though two-way traffic persists in some areas. · Medium confidence
- Bike sceneryBeautiful3.9
Rural rolling roads with reservoir and foothill views. · Medium confidence
- WindSome wind3.2
Wind was noted on the reservoir swim. Little else is documented. · Low confidence
Course traits, not part of the score
- Bike speedAverage3.4
Fast dam descent and rolling roads. 579 m (1,900 ft) of gain is moderate for 90 km (56 mi). · Low confidence
- Bike flatnessRolling3.0
579 m (1,900 ft) over 90 km (56 mi) sits mid-range. · Medium confidence
- Bike simplicitySome technical parts3.2
Fast dam descent and neighbourhood streets with some turns. · Low confidence
Run
Crowds, aid stations, conditions underfoot and scenery. Counts for 13% of the overall score.
- Crowd supportStrong3.9
Spectators line the Greenbelt run, and the 2025 race had more than 1,100 volunteers. · Medium confidence
- Aid stationsGood4.3
Ice at every aid station and cooling tents in 2026. · Medium confidence
- Run sceneryBeautiful4.0
River Greenbelt, parks and a downtown finish. · Medium confidence
- Run conditionsModerate3.0
Shaded and flat, but heat above 38 °C (100 °F) in recent years. · Medium confidence
Course traits, not part of the score
- Run flatnessFlat4.6
Flat two-loop run along the Boise River Greenbelt. · Medium confidence
Conditions
Air temperature, how predictable the weather is, setting, and spectating. Counts for 15% of the overall score.
- Air temperatureHarsh1.7
Race-date highs were 34-41 °C (94-105 °F) from 2022 to 2026. · High confidence
- Weather reliabilityVariable2.8
Reliably hot, but hail and thunderstorms were reported in one year and smoke can affect air quality. · Low confidence
- Venue beautyLovely4.1
Reservoir hills plus a river-park finish in a mountain-backed city. · Medium confidence
- Spectator friendlySome viewpoints3.4
The swim is remote, but the Greenbelt run and finish are easy to watch. · Low confidence
Course traits, not part of the score
- Low altitudeModerate3.2
About 820 m (2,700 ft) above sea level, a mild altitude effect. · Medium confidence
Stay and travel
Hotels, walkability, getting there, and the town around the race. Counts for 11% of the overall score.
- Hotel availabilityGood3.8
Mid-sized city with a field of about 1,600. No sell-outs reported. · Low confidence
- Hotel valueGood3.5
No price data found; typical for a mid-sized US city. · Low confidence
- WalkabilitySome driving3.0
Downtown hotels are near the finish, but the swim at Lucky Peak is 20+ km (12+ mi) away by shuttle. · Low confidence
- Travel easeEasy3.5
Boise Airport (BOI) is close to town but less connected than major hubs. · Medium confidence
- LogisticsSome complexity2.6
Shuttles leave about 03:30 for the reservoir swim, while the bike transition is downtown. · Medium confidence
- Town and foodGood4.0
Lively downtown with a river park and good dining. · Low confidence
Key facts
- Location
- Boise, Idaho, United States
- Typical month
- July
- Latest or next date
- 24 July 2027
- Organiser
- IRONMAN
- Field size
- About 1,600 athletes
- Distances
- 1.9 km (1.2 mi) swim, 90 km (56 mi) bike, 21.1 km (13.1 mi) run
- Swim venue
- Lucky Peak Reservoir (Barclay Bay / Turner Gulch) (reservoir)
- Bike climbing
- 579 m (1,900 ft)
- Bike laps
- 1
- Run laps
- 2
- Run shade
- Largely shaded along the Boise River Greenbelt
- Air temperature
- 15–40 °C (59–104 °F)
- Humidity
- dry
- Altitude
- 820 m (2,690 ft)
- Nearest airport
- Boise Airport (BOI)
- Where to stay
- Downtown Boise, Boise River Greenbelt, Julia Davis Park area
- Booking
- Mid-sized city with a downtown hotel core; field c.1,600.
What racers and reviewers say
- RaceRaves (2026 reviewer)Raced 2026 · aggregator · Positive
Rated the race 4 out of 5, calling Boise a great host and the half marathon along the Greenbelt their favourite leg, with a good mix of hills and flats on the bike. They were disappointed the swim was cancelled but respected a difficult call given conditions.
- Boise State Public Radio 2026 previewRaced 2026 · article · Mixed
Previews a field of about 100 pros and 1,500 age-groupers, triple-digit heat, ice at every aid station, cooling tents, a 03:30 (3:30 am) shuttle start and wide road closures on Highway 21, Julia Davis Drive and Federal Way.
- KIVI / Idaho News 6 on the 2025 returnRaced 2025 · article · Positive
Covers the return after a decade: a swim from Turner Gulch into Barclay Bay, a fast dam descent (48 mph / 77 km/h (47.8 mph) clocked), Greenbelt run, over 2,000 participants, 1,100+ volunteers and $32,000 raised for charity.
- Challenged Athletes Foundation 2025 blogRaced 2025 · blog · Positive
Recap of athletes with disabilities racing Boise 2025; notes cold reservoir water, crowds lining the route and a scenic run through neighbourhoods and shaded trees.
- Slowtwitch forum 'We Noticed' threadRaced 2026 · forum · Mixed
Pro-race discussion for 2026; a winner described the bike as a solo ride most of the day. Little course or conditions detail.
Show 2 more
- Triathlete: Magali Tisseyre race reportarticle · Mixed
Pro's account of her first 70.3 win, with a sunny start then thunder, lightning, hail and rain on the bike (from search summary; page paywalled). Year unclear.
- Slowtwitch 2010 race reportRaced 2010 · article · Mixed
Older pro report: a close finish decided by 10 seconds on a tough, cramp-inducing run day.
Sources
Pages we used for facts and ratings. See how we rate.
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