The calculated distance (air line) between Zumarraga and Donostia / San Sebastián is approximately 23 miles respectively 37 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 Zumarraga and Donostia / San Sebastián has been calculated here.
Air line (approximately)
37 kilometers
20 nautical miles