The calculated distance (air line) between Hendaye and Donostia / San Sebastián is approximately 11 miles respectively 17 kilometers.
By car or train, the actual journey to Donostia / San Sebastián is certainly longer, as only the direct route (as the crow flies) between Hendaye and Donostia / San Sebastián has been calculated here.
Air line (approximately)
17 kilometers
9 nautical miles