Biarritz Pays Basque Airport: Skip the pre-booked private transfer unless you are arriving very late or carrying serious surf gear. Take the local Chronoplus/Txik Txak bus from the airport toward central Biarritz; the evidence lists Line C and also No. 8 serving the airport, so check the live operator timetable for the correct downtown-bound stop and departure. Allow roughly 20–30 minutes to the centre and about €1.50–2. A taxi is quick but poor value for a very short trip.
Biarritz train station (Gare de Biarritz): The station is about 3 km south-east of the seafront, not in the centre. Take the local No. 2 bus toward the beachfront/central Biarritz: allow about 15–20 minutes and roughly €1–2. A taxi is reasonable with luggage, but do not assume the station is walkable with bags; the route is uphill in places.
Bayonne train station (Gare de Bayonne): Use Bayonne only if its train timing is markedly better than Biarritz’s. Continue by local bus into the Biarritz–Anglet–Bayonne conurbation; the evidence identifies Line C as linking the airport, Biarritz station and Bayonne station. Allow about 35–50 minutes to central Biarritz, plus waiting time, for a local-fare ticket. It is functional, not glamorous.