The calculated distance (air line) between Guardamar del Segura and Sant Joan d'Alacant is approximately 25 miles respectively 40 kilometers.
By car or train, the actual journey to Sant Joan d'Alacant is certainly longer, as only the direct route (as the crow flies) between Guardamar del Segura and Sant Joan d'Alacant has been calculated here.
Air line (approximately)
40 kilometers
21 nautical miles