IRONMAN Switzerland Thun 2027

Ironman Switzerland Thun sends athletes into Lake Thun for a 3.8 km swim in water that can sit around 17 degrees Celsius, then asks them to ride 180.2 km and run a full 42.2 km marathon before the finish. The race is based in Thun in the Bernese Oberland, with the long-course Ironman format at its center: cold open-water swimming, a full-distance bike leg, and a marathon on tired legs. The bike course goes through the green hinterland around Thun, while the run follows Lake Thun, keeping the water and mountains close for much of the day. Thun adds its own setting to the Swiss Ironman story, with historic bridges, clear lake water, and a mountain backdrop around the race area. The event spent 23 years in Zurich before moving to Thun, so it carries an older Swiss Ironman history into a smaller alpine-lake venue. The day draws both full-distance triathletes and spectators watching from the course and event grounds.