The calculated distance (air line) between Saint-Maximin-la-Sainte-Baume and Marseille is approximately 26 miles respectively 42 kilometers.
By car or train, the actual journey to Marseille is certainly longer, as only the direct route (as the crow flies) between Saint-Maximin-la-Sainte-Baume and Marseille has been calculated here.
Air line (approximately)
42 kilometers
23 nautical miles