The calculated distance (air line) between Santander and Aguilar de Campoo is approximately 52 miles respectively 83 kilometers.
By car or train, the actual journey to Aguilar de Campoo is certainly longer, as only the direct route (as the crow flies) between Santander and Aguilar de Campoo has been calculated here.
Air line (approximately)
83 kilometers
45 nautical miles