IRONMAN 70.3 Boulder

June 14, 2025

IRONMAN 70.3 Boulder is more than just a "half" IRONMAN. It's a cherished experience at the foot of the Rockies in one of America's hubs for elite athletes.

Nestled at the foot of the stunning Flatirons, Boulder, Colorado, is already a wildly popular home-base and vacation destination for world-class triathletes. The city's health-conscious culture, near-perfect weather and breathtaking natural environment make it a favorite on the IRONMAN circuit. 

The 70.3 offers athletes the chance to focus on their performance and prep for future full IRONMAN opportunities.

Stay in Boulder and maximize your pre- and post-race time, and arrive to the start line fresher. View the IRONMAN 70.3 Boulder hotel options here.
 

IRONMAN 70.3 Boulder 2025 Event Information

The 2025 race starts at the Boulder Reservoir with a single-loop swim, followed by a 56-mile bike traversing rolling hills, and lastly, ends with a two-loop, 13.1-mile running course. Spectators will have multiple opportunities to cheer on the athletes for a triumphant finish.

For more information, visit the official IRONMAN 70.3 Boulder website.

For details on the IRONMAN Foundation’s Humanitarian Relief efforts, and how to donate, purchase t-shirts, or volunteer, go to the foundation's website.

Course Map

View the IRONMAN website for interactive course maps.

IRONMAN Humanitarian Relief Efforts

The IRONMAN Foundation has provided more than $60 million to more than 10,000 local, regional, national and global nonprofit initiatives since 2003. Learn more about their efforts and how to donate, purchase t-shirts, or volunteer, on the Foundation's website.