The calculated distance (air line) between Sainte-Marie and Les Trois-Bassins is approximately 21 miles respectively 34 kilometers.
By car or train, the actual journey to Les Trois-Bassins is certainly longer, as only the direct route (as the crow flies) between Sainte-Marie and Les Trois-Bassins has been calculated here.
Air line (approximately)
34 kilometers
19 nautical miles