Diamond Mountain Triathlon

Welcome to Diamond Mountain Triathlon, hosted in the scenic heart of Harriman State Park. The course features a calm lake swim, a rolling 15-mile bike loop with spectacular views, and a fun lakeside run to the finish. The event is beginner-friendly while still rewarding strong competitors. Rain or shine, we race — and we’re excited to share the course with you. What the event offers: Relaxed and convenient midday start Police-controlled intersections Course signage and volunteer support Race photographers Free public parking Junior athletes race Duathlon with adults for free Junior athletes race Triathlon for free and may have a separate start Finisher medals for all participants Awards for Top-3 Men & Women in both Triathlon and Duathlon Overall Adult Triathlon Winners are getting champion suit: Free jersey for Triathlon participants: Duathlon participants are getting running jersey Follow our race at @Diamond_Mountain_Races Race Schedule Date: Sunday, September 20 Start Time: 12:00 PM Cutoff: 2:20 PM Awards: ~10 minutes after Top-3 Women finish (Triathlon + Duathlon) Race Location: Lake Welch Beach 800 Kanawauke Rd, Stony Point, NY 10980 Only the Kanawauke Rd entrance is open before the event (Exit 14 at Palisades Pkwy) Race course: Triathlon: 0.5mi swim in Lake Welch. Biking is one 15-mile lap around the park, Strava record is here . 2 mile run, Strava record is here . Duathlon: Both runs are the same: 2 miles, Strava record is here . Biking is one 15-mile lap around the park, Strava record is here . Transition at Lake Welch picnic area. See maps on the bottom of the page. Registration for Triathlon and Duathlon: Check-in opens 1 hour before start and closes 20 minutes before start. Online registration is recommended — it keeps things smooth and helps avoid mistakes at the table. Bike Race Info: Interested in the cycling race at the same venue? Registration for the Diamond Mountain Classic is at: BikeReg.com/DMC Note: you can participate only in one r