Afternoon,
If you want to go across Europe to get to Greece, you’re dependent on trains which didn’t run this year and may or may not run next year; these are Belgrade to Thessalonike and Sofia to Thessalonike. I think provided a degree of normality has resumed by next summer we can be hopeful that at least one of those (more likely the latter) will have resumed by then, but don’t quote me on that! Before the pandemic the train from Sofia occasionally even ran from Bucharest, which might be useful once again in the future.
The other option, and the only one that’s currently viable, is to take one of several ferries across the Adriatic from Italian ports. Look carefully when booking, as some are technically “included” in the pass (meaning using them will use up a travel day and you will only be charged for port charges, accommodation upgrades, etc.), while some are discounted with the pass (no travel day used, but you buy a ticket in the normal way which is then reduced by typically 30%).
The ferry from Piraeus to Crete will be of the latter type - reduced rather than included. In order to get there from Patras (where ferries from Italy arrive) you’ll need to take an Interrail-covered bus-train combo to Athens, as the railway line that links the two still hasn’t been completely recommissioned following the Greek financial crisis of a decade ago.
For all other travel in Greece, bear in mind that since the associated closure of the narrow-gauge network around the Peloponnese there is only, to all intents and purposes, one main railway line in the country, and most Greeks themselves get around via a variety of regional coach companies branded KTEL. It’s not all that easy to get information about timetables and prices for KTEL buses abroad, so it may sometimes be a case of seeking help with this at local tourist information centres once you’re there.
Thanks for taking the time to write such a detailed and informative reply.
I'll certainly take everything you've mentioned in to account when finally booking.
Thanks again,