Travel from Bilbao to San Sebastian

You could take the train.

To be more precise, Euskotren will get you there in about 2 3/4 hours with lots of stops. Hourly departures. Bilbao Matiko is the main station in Bilbao. In Basque, San Sebastian is called Donastia. Terminal station on the E1 line is Amara-Donastia/San Sebastian.
https://www.euskotren.eus/en

To be specific the narrow gauge train which runs hourly, and takes just over 2 hours.

There is also the regular inter city bus service.

The main line train is not really suitable as you have to change at Mirando de Ebro, with a long wait, so the journey takes 4 to 5 hours.

The Euskotren line between Bilbao and San Sebastian is quite scenic, but it is very, very slow. It's worth going that way if you have extra time, but most folks would take the bus. Buses run frequently. I believe the major companies on that route are ALSA and Avanza/PESA.

I would not take the train in this route, it does not make sense as it´s a commuter train that stops in every town on the way. Bus is the most logical option and it´s what everybody uses here. Pesa and Alsa are the bus companies that cover this route, over 30 daily departures. Can´t go wrong with our comfortable, cheap, clean, safest bus system.

I would definitely use Mikel for private transportation. He's amazing and we have used him for 4 yrs. My husband walks w/a cane. Contact [email protected] phone 34 618 550 395. he's the best