The calculated distance (air line) between Sant Vicenç dels Horts and Castelldefels is approximately 8 miles respectively 13 kilometers.
By car or train, the actual journey to Castelldefels is certainly longer, as only the direct route (as the crow flies) between Sant Vicenç dels Horts and Castelldefels has been calculated here.
Air line (approximately)
13 kilometers
7 nautical miles