Marseille-Aix is a late-winter trail race in the Bouches-du-Rhône, connecting Marseille with Aix-en-Provence over a 42 km route with 1,023 m of climbing. Runners depart Marseille and spend much of the course in the pine forests of the Massif de l'Étoile before finishing in Aix. A shorter 12 km option runs from Gardanne to Aix with 240 m of elevation gain, offering newer trail runners a more accessible way into the event.
The 42 km race can be run solo or as a two-person relay, with the changeover in Simiane after a first leg of 24 km and 646 m of climbing; the second runner then covers 18 km with 377 m of climbing. All races conclude in Parc Jourdan in central Aix-en-Provence, including the children's races, which range from 400 m to 3,000 m depending on age. The event is presented as a “Mise en Bouche du Rhône,” a playful nod to the region and to Marseille-Cassis, the older Marseille race that provides this newer Marseille-to-Aix trail its clear point of comparison.