The calculated distance (air line) between Sainte-Luce and Gros Islet is approximately 28 miles respectively 45 kilometers.
By car or train, the actual journey to Gros Islet is certainly longer, as only the direct route (as the crow flies) between Sainte-Luce and Gros Islet has been calculated here.
Air line (approximately)
45 kilometers
24 nautical miles