Ferries are not included, however some operators offer a discount (10-50%) on their normal fares for passholders.

From experience this discount normally only includes the travel ticket, not extras such as cabins so it is relatively small.

Viking lines, Finnlines and Tallink Silja are the ferry compnies sailing Finland - Sweden, I’d suggest you check their websites and all the routes available and see which times/dates/prices suit you best including travel to/from whichever ports they serve as a shorter sea crossing + train will often be much quicker than a direct long ferry.

Recent notes said that some have much curtailed their previous fairly often trips. TLN-STO direct CAN be done, but only ev 2nd day-via HEL more often and it may even work out cheaper. In fact 1 of these ferries is now used to house asylum seekers here in NL.

The DAYtime ferries Turku-STO are much recommended-very cheap and very good views of the many islands and long entry into STO. Also cheap food and entertainments on board and ´cheap for Scandi´ tax-free sales. Except for a very few hi-peak summer days you do not have to worry about RES-can even buy ticket just before ship goes-via app is cheaper.

ONE of the traditional 2 (viking=red and Slja, now merged with Tallink=white/blue) offered free passage to passholders (but you had to pay port+some other taxes, and I guess by now also for fuel), but I am not sure if this still applies (for STO-Turku). Forget those maps-out of date and imprecise-a curse for the überpünktlich Deutsche who use old-style DB child-playlets.

It doesn't, as you can easily see on the benefits portal.