Dear All Community member,
I have plan to visit Interlaken and Zermatt next December (exact date on December 24th, and December 25th) each trip take from Basel. I have seen the schedule on the eurail app, which state that seat reservation optional.
I do not have experience to visit both places before during christmas holiday. May I ask your suggestion whether it is necessary to book seat reservation for both trip during christmas holiday? Thank you for your help.

