I am heading to Spain in 1 week and will be flying into Bilbao and arriving at about 4pm. Does anyone know the best way to get to Santillana del mar (we don't really want to hire a car) and is it achieveable to get there by about 6pm in the evening?

Also any tips on the best way to get from Bilbao to San Sebastian? How long does it take?

Thanks travellers!

It is completely impossible to do it by public transport. With public transport (Getting a bus from Bilbao to Torrelavega at 6:30 pm, you´d arrive there at about 8:25 pm and then you should get another bus to Santillana del Mar (if you´re a lucky you could get a bus at 8:30 pm but if not you must wait until 10:30pm)

If you´re in a hurry rent a car; is the solution

Also, I forgot to tell you.
To get from Bilbao to San Sebastian simply get a bus; it is the fastest way; It takes 1 hour and 15 minutes and it costs 6,20€ a single trip and 11,55€ a round trip.
Be careful not to get a bus which stops in every station because that can take 2 hours -The only one which do that departing from Bilbao is at 5:30 pm-
There are also two first class services which run from Bilbao at 12:00 and 8:00 pm that cost the double.

No way to be in Santillana by 6pm unless you rent a car:
allow at least half an hour to reach Termibus coach station in Bilbao. A coach to Santander (www.alsa.es) takes about 75 to 9O minutes, and then from Santander to Santillana... I can not be very helPful on this Part...(no idea if there are only buses or also trains.... check www.movelia.es for buses or www.renfe.es for trains)

There are 2 coach companies travelling between Bilbao and San Sebastian: PESA has many connections a day; ALSA some less. If you take the direct service is about 1 hour.