Marathons Events in Boulder

Check out happening marathons events all around Boulder, CO

Tri Boulder Sprint, Olympic & Long Course

 Sat, 18 Jul at 07:15 am Boulder Reservoir

Boulder Peak Triathlon, Duathlon, & Aquabike

 Sun, 12 Jul at 07:15 am Boulder Reservoir

Harvest Moon Long Course Triathlon

 Sun, 31 May at 07:15 am Boulder Reservoir

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

 Sat, 06 Jun at 07:15 am Boulder Reservoir

Boulder Sunrise Triathlon

 Sun, 28 Jun at 07:15 am Boulder Reservoir

Boulder Rez Marathon

 Sat, 15 Aug at 07:15 am Boulder Reservoir

Boulder Stroke and Stride Series

 Thu, 04 Jun at 05:00 pm Boulder Reservoir

Grit2Greatness Endurance Training Camp 2026 - Boulder, CO

 Thu, 25 Jun at 08:00 am Boulder Reservoir Free

Peony Virtual Race | 1M 5K 10K 13.1 26.2 | Language of Flowers Collection

 Sat, 30 May at 01:00 pm Boulder USD 4 to 42

Race Through Hawaii Virtual Race | 5K, 10K, Marathon | Run Anywhere

 Sat, 16 May at 01:00 pm Boulder USD 5 to 42

Memorial Day 1M 5K 10K 13.1 26.2

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

Lavender Virtual Race 1M 5K 10K 13.1 26.2 | Language of Flowers Collection

 Sat, 27 Jun at 01:00 pm Boulder USD 4 to 42

Day of the Dog Virtual Race 1M 5K 10K 13.1 26.2

 Sat, 22 Aug at 01:00 pm Boulder USD 4 to 42

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

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

Cat Day Virtual Race 1M 5K 10K 13.1 26.2

 Sun, 09 Aug at 01:00 pm Boulder USD 4 to 42

Unhinged and Feral 1M 5K 10K 13.1 26.2 - Now Only $18!

 Sat, 03 Oct at 01:00 pm Boulder USD 0 to 42

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

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

2026 Race to Read 1M 5K 10K 13.1 26.2

 Fri, 06 Mar at 01:00 pm Boulder USD 5 to 42