| 421 | 22 Jun 25 | 2025 Cohasset Triathlon | triathlon | Cohasset, MA |
| 422 | 05 Oct 25 | 2025 Cohutta Triathlon | triathlon | Crandall, GA |
| 423 | 22 Jun 25 | 2025 Colonial Beach Triathlon | triathlon | Colonial Beach, VA |
| 424 | 07 Jun 25 | 2025 Colorado Triathlon | triathlon | Boulder, CO |
| 425 | 20 Jul 25 | 2025 Columbia Association Kids Triathlon | triathlon | Columbia, MD |
| 426 | 22 Jun 25 | 2025 Columbia Association Triathlon . . | triathlon | Columbia, MD |
| 427 | 08 Aug 25 | 2025 Columbia River Kids Triathlon & All Age Sunset Run 5K & 10K - Friday | triathlon | Vancouver, WA |
| 428 | 09 Aug 25 | 2025 Columbia River Triathlon | triathlon | Vancouver, WA |
| 429 | 24 May 25 | 2025 Columbia Swim youth triathlon race simulation clinic . . | triathlon | Sunnyvale, CA |
| 430 | 14 Jun 25 | 2025 Conneaut Lake Sprint Triathlon | triathlon | Conneaut Lake, PA |
| 431 | 14 Sep 25 | 2025 Cool Sommer Mornings Sprint Triathlon, Duathlon & 5K #4 | triathlon | Clermont, FL |
| 432 | 15 Jun 25 | 2025 Cool Sommer Mornings Tri Series #1 - SUNDAY | triathlon | Clermont, FL |
| 433 | 10 Aug 25 | 2025 Cool Sommer Mornings Triathlon & 5K Series #3 | triathlon | Clermont, FL |
| 434 | 13 Jul 25 | 2025 Cool Sommer Mornings Triathlon Series #2 | triathlon | Clermont, FL |
| 435 | 13 Jul 25 | 2025 Cornhusker State Games Triathlon | triathlon | Valley, NE |