13_13 is a 24-hour running event at Baggersee Rossau in Innsbruck, Austria. Runners complete laps on a flat 5 to 6 km loop, choosing their own total distance. The event emphasizes time on course: solo runners set their own pace, and relay teams of 2 to 8 people can share the running duties throughout the day and night.
The loop consists of gravel and asphalt sections and is designed for running after dark. The course remains the same as daylight transitions to night. Between laps, runners can return to the Basecamp to rest, eat, or switch teammates, remaining engaged with the event even during breaks. The focus is on participating within the 24-hour format, rather than achieving a specific result, whether that involves completing numerous laps, taking breaks, or supporting a team's continuous effort.