100X100 Swim 2026

100X100 Swim is a pool challenge based on a simple concept: swim 100 repeats of 100 meters. This totals 10 kilometers, or 6.1 miles. One variation is the Birthday Swim, where the swimmer completes the full set on their birthday. It is not limited to a specific venue or date; the set can be completed in any pool, with the occasion providing the workout its customary feel. The format originated from triathlon training, after a professional triathlete observed coach Brett Sutton assigning 100x100s to a group for an athlete’s birthday. The main difficulty lies not in navigation or terrain, but in remaining in the water for three to five hours while repeating the same distance repeatedly. It is suitable for swimmers and triathletes who have trained for extended pool sessions, as a six-mile swim requires planning, pacing, and sufficient perseverance to resist the inclination to stop early.