We are planning to go from Bilbao to Marseilles. After some research, it seems it is not viable to travel to France from Bilbao, so going to Barcelona seems essential.
From Barcelona, there is a high speed train to Toulouse, and then we can take a train to Marseilles. Is the high speed valid on Interrail Global pass?
If not, is there another route which is valid from Barcelona to Marseille?
As far as I can tell there is only one daily train from Barcelona to Toulouse, RSC 9726. Someone do correct if wrong. According to the interail railpanner app your pass will be accepted but you will need to buy an additional compulsory reservation for a fee of €15 euro (https://www.interrail.eu/en/plan-your-trip/trains-europe/high-speed-trains/renfe-sncf-high-speed-train) However, this train arrives into Toulouse too late for the last connection to Marseille.
In addition, the direct trains from Toulouse to Marseille are operated by intercities, the man in seat 61 (https://www.seat61.com/InterRail-pass-guide.htm#France) lists the reservation fee as €6.
I did this exact journey by interrail as well on my trip but unless you want to go to Toulouse it represents a big detor. The fastest way is to get the fast train to Montpellier and them the local to Marseille. You'll need a reservation for the first train for €15. There is also a daily through train (RSC 9724) which leaves at 1645 and arrives at 2126. The reservation fee is €19 on the direct train (https://www.interrail.eu/en/plan-your-trip/trains-europe/high-speed-trains/renfe-sncf-high-speed-train) your looking at a journey in the region of 5 hours.
Or you could do what I did and use local trains instead, it's slower but free. Your looking at a journey time of a little over 9 hours with a change in Cerbere and Avignon or Montpellier.
