70.3 Boulder

Saturday 13 June 2026
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US Boulder, Colorado, United States
Ironman 70.3 Boulder will be held at the Boulder Reservoir. The race, the first-ever Ironman 70.3 in the region, will bring spectacular views of the Rocky Mountains, a challenging course, solid competition and strong volunteer support. Ironman 70.3 Boulder will serve as one of more than 35 worldwide qualifying events for next year's Foster Grant Ironman World Championship 70.3 in Clearwater, Fla. Swim: 1.2 miles The swim will consist of one lap in the Boulder Reservoir. The start will be from the right (or east) of the public swim area, and the finish will be past the Pavilion Building, directly "above," or north, of the Transition Area. Bike: 56 miles The course starts at the Boulder Reservoir parking lot, heads south on 51st to Jay road and west to Highway 36. Rolling along 36 north towards Lyons , the first aid station is at mile 6. Continue along 36 and turn east on St. Vrain Road . Enjoy the smooth pavement downhill of St. Vrain Road to where it "t's" at 75th Street. Make a right on 75th, and continue all the way as it turns into 73rd. We will make a right turn on Monarch Road (at IBM), going down Monarch for 0.6 mile before making a u-turn back to 73rd. Once back at 73rd, make a right and continue to the Diagonal. This turnaround on Monarch will be done on both loops. Head south west on the Diagonal toward Boulder , Right on Jay road, and continue on Jay for the second loop on the same route. When you reach Jay and 51st after your second loop, make a right and return north on 51st street back to the Reservoir. Run: 13.1 miles The start is at the bike transition area on the south side of the Reservoir near the main pavilion. Run west on the asphalt/gravel to the front gate. Turn right and continue north on 55th Street, passing Monarch road, going about halfway to Niwot Road. Turn around at the Turn-Around marker, go back to Monarch Rd. and turn left and head east on Monarch to the Canal Road entrance. Pick up the canal road and head south around the


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