The Boulogne Mixed Relay Triathlon is a short team race held in Boulogne-Billancourt, west of Paris. Four athletes compete in a fixed order: woman, man, woman, man. Each teammate completes a short triathlon: 250 metres swimming in the Seine, 5.6 km cycling, and 1.8 km running, before handing over the relay. If the swim is cancelled, the event becomes a duathlon. The race takes place in October and is open to youth categories from Benjamins through Juniors, with teams composed of two women and two men.
The cycling section is the most demanding part of the course: 5.6 km divided into four 1.4 km laps on a road closed to traffic. It features 180-degree turns and allows drafting. The run is also compact, consisting of an 800-metre first run and a 1.6 km second run over two laps. The event emphasizes relay tactics and team order over individual pacing. Its own materials describe it as a competition focused on team cohesion, strategy, self-sacrifice, and shared effort.