Marathons Events in Boulder

Check out happening marathons events all around Boulder, CO

Boulder Peak Triathlon, Duathlon, & Aquabike

 Sun, 12 Jul at 07:15 am Boulder Reservoir

Boulder Rez Half Marathon

 Sat, 11 Apr at 08:00 am Boulder Reservoir

Colorado Triathlon (Sprint, Olympic, Duathlon, & Aquabike)

 Sat, 06 Jun at 07:15 am Boulder Reservoir

Chelsea Sodaro: An Unlikely Journey to Triathlon, Motherhood, and Ironman World Champion

 Wed, 18 Mar at 07:30 pm Chautauqua Community House

Boulder Stroke and Stride Series

 Thu, 04 Jun at 05:00 pm Boulder Reservoir

Be Kind to Your Mind 1M 5K 10K 13.1 26.2

 Sat, 02 May at 01:00 pm Boulder USD 4 to 42

Consider the Wildflowers 1M 5K 10K 13.1 26.2

 Sun, 01 Mar at 01:00 pm Boulder USD 4 to 42

2026 Be Brave 1M 5K 10K 13.1 26.2

 Sat, 07 Mar at 01:00 pm Boulder USD 4 to 42

Race for Love 1M 5K 10K 13.1 26.2

 Sat, 14 Feb at 01:00 pm Boulder USD 4 to 42

2026 New Year Challenge -Year of the Horse 2.026 Mile 20.26 Mile 202.6 MILE

 Sun, 15 Feb at 01:00 pm Boulder USD 4 to 42

2026 Taco Sloth 1M, 5K, 10K, 13.1, 26.2

 Sun, 22 Feb at 01:00 pm Boulder USD 4 to 42

Memorial Day 1M 5K 10K 13.1 26.2

 Mon, 25 May at 01:00 pm Boulder USD 4 to 42

2026 First Responders 1M 5K 10K 13.1 26.2

 Sat, 28 Mar at 01:00 pm Boulder USD 4 to 42

2026 Race Alotl for the Axolotl 1M 5K 10K 13.1 26.2

 Sun, 08 Mar at 01:00 pm Boulder USD 4 to 42

Harvest Moon Long Course Triathlon

 Sun, 31 May at 07:15 am Boulder Reservoir

Luck of the Irish 5K

 Tue, 17 Mar at 01:00 pm Boulder USD 4 to 42

2026 Day of the Dead 1M 5K 10K 13.1 26.2

 Sat, 14 Mar at 01:00 pm Boulder USD 4 to 42

2026 The Truth is Out There 1M, 5K, 10K, 13.1, 26.2

 Fri, 20 Mar at 01:00 pm Boulder USD 4 to 42

2026 World Cancer Day 1M 5K 10K 13.1 26.2

 Sun, 01 Feb at 01:00 pm Boulder USD 4 to 42

Mother's Day 1M 5K 10K 13.1 26.2

 Sun, 10 May at 01:00 pm Boulder USD 4 to 42