What ferries go from Sweden to Finland? [closed]

Too many to sensibly summarize in an answer that would soon be out of date, but the two core routes with the best schedules, largest ferries and usually cheapest prices are Stockholm-Helsinki and Stockholm-Turku, with the two largest operators on both being Viking Line and Tallink Silja. Direct Ferries has a more thorough list of options.

Beware that pricing is complicated, and it's often much cheaper to book a "cruise" and throw away the return than to get a regular one-way.

Adding some information about Viking line- it's free to become a member and in return you get discounts. Viking line also sails from Kapellskär (100km north of Stockholm) to Mariehamn which is technically Finland. You can make a round trip in half a day, and it is free for members. The prices to Turku and Helsinki varies, but again members get good deals down to a few hundred Kronas to a family. The catch ? they want you to buy cheap alcohol and tobacco on board.