The calculated distance (air line) between Sant Andreu de Llavaneres and Sant Martí is approximately 18 miles respectively 29 kilometers.
By car or train, the actual journey to Sant Martí is certainly longer, as only the direct route (as the crow flies) between Sant Andreu de Llavaneres and Sant Martí has been calculated here.
Air line (approximately)
29 kilometers
16 nautical miles