From Bilbao Airport:
There is a bus service (every hour) from Bilbao Airport to the city of San Sebastian. It takes 1h15 and the price is around 15.40€ (payable to the driver). The bus stops is on the road as soon as you get out from baggage claim.
In Donostia-San Sebastian, the bus from Bilbao Airport stops here:
From San Sebastian Airport
There is a bus service from San Sebastian Airport to the city, which takes about 30 min. and costs 2,10 €. You can check the timetable here.
In Donostia-San Sebastian, the bus from San Sebastian Airport stops here:
The main rail station in San Sebastian is here:
Information about San Sebastian
For more information about the city of San Sebastian: www.sansebastianturismo.com