MARSeille BLEU takes place at Parc Borély in Marseille during March, coinciding with colorectal cancer screening month. Adults can participate in a 2.5 km walk or a free-pace run, or opt for a timed 5 km race. Children aged 6 to 11 have their own 800 m races. Participants are encouraged to wear blue, and the event highlights a key health message: improved screening could prevent 10,000 deaths annually in France.
The day begins with a warm-up and music before the children's races, the walk, and the timed adult 5 km. A health village offers information on nutrition, physical activity, and screening, alongside family entertainment, food, music, and prize ceremonies. The event is organized with support from SMUC, the city of Marseille, and CRCDC Paca. Former Marseille footballer Basile Boli is the patron and presents trophies. Having reached multiple editions, the event also emphasizes practical and eco-responsible aspects, such as not providing T-shirts and asking participants to bring their own water bottles.