From Stockholm, Silja and Viking Line ships cross to the Finnish Åland Islands (7 hours), Turku (11 hours), and Helsinki (15 hours), generally with one departure daily in each direction.
Finland is still a major shipbuilding nation, and the ferries that cruise the Baltic to the Finnish Åland Islands and Sweden seem more like luxury liners. Facilities might include saunas, children's playrooms, casinos, a host of bars and cafés, and superb restaurants. There are storage boxes for luggage in the Helsinki and Stockholm terminals if you are planning a day of sightseeing in either city.
In Helsinki the Silja Line terminal for ships arriving from Stockholm is at Olympialaituri (Olympic Harbor), on the west side of the South Harbor. The Viking Line terminal for ships arriving from Stockholm is at Katajanokkanlaituri (Katajanokka Harbor), on the east side of the South Harbor. Both Silja and Viking have downtown agencies where information and tickets are available. Ask about half-price fares for bus and train travel in conjunction with ferry trips.
Silja Line (0600/15700 in Helsinki. www.tallinksilja.com.)
Viking Line (0600/41577 in Helsinki. www.vikingline.fi.)