The calculated distance (air line) between Kaesŏng and Ganghwa-gun is approximately 16 miles respectively 26 kilometers.
By car or train, the actual journey to Ganghwa-gun is certainly longer, as only the direct route (as the crow flies) between Kaesŏng and Ganghwa-gun has been calculated here.
Air line (approximately)
26 kilometers
14 nautical miles