This is extract from information for Bilbao to SJPdP. Just get off in Irun.
1650 Bilbao to SJPdP via Bayonne
1651 This section discusses transportation from Bilbao to SJPdP via Bayonne.
Index 1650
1652 Bilbao Airport to Bilbao Termibus
1653 Bilbao to Bayonne Bus Option
1654 Bilbao to Hendaye Euskotren Option
1655 Bilbao to Irun Bus Option
1652
Bilbao Airport to Bilbao Termibus
Bizkaia buses #A3247 travels from Bilbao airport to Bilbao Termibus where it terminates. Termibus is located in same area as San Mames station.
1653
Bilbao to Bayonne Bus Option
There are PESA buses twice daily (except Sunday) from Bilbao Termibus to Place de Basques Bayonne.
Chronoplus bus #5, 8, B, or N departs from Place de Basques to Gare de Bayonne.
PESA
http://www.pesa.net/pesa/public_home/ctrl_home.php
1654
Bilbao to Hendaye Euskotren Option
Take Metro from San Mames to Etxebarri Station or take Euskotren Transvia tram to Atxuri Station.
Euskotren commuter trains travel from Atxuri Station and Etxebarri Station to Hendaia station, co-located with SNCF Gare d'Hendaye France, where Euskotren tracks terminate. A transfer is required at San Sebastian Euskotren Amara station.
Irun Euskotren Colon Station is close to Irun Renfe Station.
Euskotren
http://www.euskotren.es/
1655
Bilbao to Irun Bus Option
See Bilbao Termibus for schedule of buses to San Sebastian bus station.
The San Sebastian bus station is an outdoor bus stop located at Plaza de Pio XII beside the Hotel Amara Plaza.
Termibus Bus Station
http://www.termibus.es/index.php?idi=es
Bus companies providing service in San Sebastian:
http://www.donostiasansebastian.com/autobuses.html
Ekialdebus provides interurban bus service from San Sebastian including service to Irun and San Sebastian Airport.
http://www.ekialdebus.net/inicio/?lang=es