I will leave here a few notes about using an Interrail pass in Spain so that people thinking of doing that can find them in the future.

First, a word about Interrail passes: they are a wonderful idea. You can buy a pass from the Interrail site that allows to take as many trains as you wish in Europe during a given period. We took the option of travelling 7 days over a period of a month, for a cost of 1232 € (for 2 adults and 3 kids, aged 16, 16 and 10).

There is a catch that is well documented: for some trains, usually the fast ones that you use to cross a country, you need to buy reservations, and these can be costly. On France fast trains, they seemed to be 30% of a normal ticket. Also, over the summer, these reservations usually need to be bought a few weeks in advance.

With my partner, we made a wonderful Interrail trip in 2003 from Belgium to Italy, Greece and ultimately Turkey (reaching Istanbul) and we hoped to show our three kids a part of this wonderful network of railways that Europe has. I also made another wonderful trip around 1994 with my parents to Spain (down to Cordova), so I knew the lines exist. This time we wanted to go to the atlantic coast of Spain, which has wonderful landscapes and beaches.

Now, for Spain, there are additional catches to take into account:

• Most trains can not be reserved online (it appears some can, but I did not find them, there were not on my trip apparently), so you need to go to a train station when reaching Spain and cross fingers that there is still some room available. So basically that makes the whole scheme unworkable.
• The trip planner found at interrail.eu always route you through Barcelone to enter Spain, while you can go to the Spanish border to Hendaye, take a 10 minutes ride on a train from the company Euskotren to Irun across the border (or walk, take a bus or a taxi, it’s really not far) and then continue by train. This is not documented anywhere and if you wish to go from Bordeaux to San Sebastiàn, you will get offered this stupid schedule:
  This looks even stupider when you visualize it on a map.
  Generally, this trip planner is not very good, it hides some options for no clear reasons sometimes (at some point, it showed us no options without reservation between Bordeaux and Nantes, while there exists one, for example) and it creates insecurity by being unreliable. It also does not show schedules for trains that are not in the pass, but that could be considered fair game.
• Now that you are in Spain, normally, you can take FEVE and RENFE trains (they are now the same company, apparently) and travel along the coast, right? In practice, what we encountered was that we went to a local train station and, as there was nobody in the station itself (in Llanes), we were connected through a video booth to somebody who did not speak English or French (this is a constant in Spain, but for a video booth aimed at travellers, you could expect some foreign language support) and that just told us that using Interrail passes was impossible on FEVE, which we were counting on for travelling along the coast (we did that in 2005, without an Interrail pass and the lines were slow, but charming).
• On top of that, finding the timetables online is a game of frustration. The websites of RENFE segments the information based on the types of trains, which obviously you don’t know before you search. I’ll let you look at the website here: RENFE timetables and I have been scratching my head a lot about why a given station was not presented on a list. A Spanish colleague of mine told me that this was a known joke/scandal in Spain. I even had to use Open Railway Map to be able to know if lines even existed (usually, they did). Google maps turned out to be the easiest way to get some information about timetables in the end but it mainly showed that buses were way more practical.

So, in the end, we did most of our travelling using buses from the company Alsa. They have decent apps and websites, low prices and connections from all the cities on the coast. Philosophically, I would have preferred to take trains from public companies than buses from private ones, but I have to say that the buses were easy to travel with. When we took trains, we paid for them too, since we were not sure that our passes would be accepted. It’s “impossible”, remember. Happily, we’ll cover the cost of the passes thanks to the travelling that we are doing in France.

Now, to finish on a good note, we had two great weeks, and I would heartily recommend visiting the region. We went to Bilbao, Llanes, Oviedo, Cudillero, Santander, San Sebastiàn and Irun, and they are all worth the trip, but Interrail is not the right option to do it.