ÖTILLÖ Swimrun World Championship

The ÖTILLÖ Swimrun World Championship is the original swimrun race and the sport’s most prestigious competition. Held annually on the first Monday in September in the Stockholm archipelago, this race covers 70 km across 25 islands—60 km of trail running and 10 km of open-water swimming. Teams of two race from Sandhamn to Utö, alternating between disciplines without transition zones, wearing wetsuits and running shoes throughout. With harsh terrain, frigid water, and more than 8 hours of exertion, ÖTILLÖ is regarded as one of the toughest single-day endurance events in the world. Only 160 teams qualify each year, based on merit from the global ÖTILLÖ Swimrun World Series or through direct invitation, making the start line as exclusive as it is demanding.