The calculated distance (air line) between Ondarroa and Gernika-Lumo is approximately 13 miles respectively 22 kilometers.
By car or train, the actual journey to Gernika-Lumo is certainly longer, as only the direct route (as the crow flies) between Ondarroa and Gernika-Lumo has been calculated here.
Air line (approximately)
22 kilometers
12 nautical miles