There's a train Krakow-Warsaw-Vilnius:

https://www.seat61.com/trains-and-routes/warsaw-to-vilnius-by-train.htm

Also Vilnius to Riga:

https://www.seat61.com/trains-and-routes/vilnius-to-riga-by-train.htm

Riga to Tallinn is also possible, but with a long wait in Valga:

https://www.seat61.com/trains-and-routes/riga-to-tallinn-by-train.htm

There are also many buses; Lux Express has a pass discount (no travel day needed).

Always check timetables with the operators and never in the rail planner app.

The trains are generally cheap so if you have a flexipass, it's often not worth using a travel day in this region.

I did the reverse in July and as posted above if you haven’t reserved the train beforehand you’ll be very lucky to get on as basically there is one train a day on each of the routes.

everyone uses buses lux, flix and euroconnect. Lux do a lounge seat which is a reclining first class seat in its own compartment I used it and thought the extra few euros well worth it.

in Riga and Vilnius the bus station and train station are very close together but in tallin the bus station and train station (baltijam) are about 5km apart one on each side of the old town, if your getting the ferry to Helsinki the port is about 2km north of the old town equidistant to both train and bus stations.

Hello, if you would like to travel to England around November 8th, we could travel together for a few days.