- The Nation's Triathlon
- 4546 people
- United States (Washington, D.C.)
The most participants in a single triathlon race of international distance was 4,546 at The Nation's Triathlon in Washington, D.C., USA, on 12 September 2010. International, or Olympic, distance triathlons consist of a 1.5 km (0.93 mi) swim, 40 km (24.85 mi) bicycle ride, and 10 km (6.21 mi) run. The event raised more than $3 million (£1.95 million) for the Leukemia and Lymphoma Society and consisted of a swim in the Potomac River, bike ride through the city's parkways, and run through the city's monuments and memorials.