Of very varying difficulties / likelihood to happen
- Visit every EU / Schengen / de-facto Schengen country by rail (except those without railways)
I'm missing Greece, Latvia and Lithuania from this set, and wanted to reach Istanbul (having got as far as Sofia before).
None of these is exactly easy at the moment, and I don't do sleepers so Istanbul is out.
Sofia-Thessaloniki is out too, with no trains across the border.
The recent train crash in Greece put me off domestic services.
The Baltics are getting better but still take a lot of time Warsaw-Vilnius-Riga-Tallinn.
I have unfinished business in Slovakia (crossed the country by rail but haven't "set foot" there yet) - had hoped to see the Tatras one day by rail.
I'd like to visit Mediterranean islands with railways (done Sicily), but the logistics for Corsica and Sardinia are too complex (ferries/flights).
Mallorca sounds too touristy, but the trip to Soller looks nice (at least on the Mallorca Files!).
I do have a 5-day Interrail ticket for 2025 but haven't decided where/when to go yet, probably DE/CZ.
Altogether I've done 25 EU/EFTA countries plus RS/UA.