The calculated distance (air line) between Biarritz and Salies-de-Béarn is approximately 32 miles respectively 51 kilometers.
By car or train, the actual journey to Salies-de-Béarn is certainly longer, as only the direct route (as the crow flies) between Biarritz and Salies-de-Béarn has been calculated here.
Air line (approximately)
51 kilometers
28 nautical miles