SF Line

Rederi Ab Vikinglinjen was founded in 1959 and began ferry services between Gräddö, Sweden, and Korppoo, Finland. The company operated the ro-ro ship Viking, which it bought that year. The ship had previously been named Dinard.

After a disagreement between the founders, Gunnar Eklund and several others left Rederi Ab Vikinglinjen and founded Rederi Ab Ålandsfärjan. The new company bought the steamer Brittany, renamed it Ålandsfärjan, and began operating between Kapellskär, Sweden, and Mariehamn, Åland. The route competed with Rederi Ab Vikinglinjen's services.

In 1966, Rederi Ab Ålandsfärjan, Rederi Ab Vikinglinjen and Rederi AB Slite formed Viking Line as a joint marketing organisation to compete with Silja Line. The three companies then ordered several new ships, and Viking Line increased its ferry services in the Baltic Sea.

In 1970, Rederi Ab Ålandsfärjan changed its name to SF Line. The "S" stood for Sverige (Sweden), and the "F" for Finland. The company's first new ship, MS Kapella, had entered service in 1967. To honour Gunnar Eklund's wife, Ellen, later SF Line ships were given names ending in "-ella".

Also in 1970, Rederi Ab Solstad merged into Rederi Ab Sally. In 1987, EffJohn, the company that owned Silja Line, bought Rederi Ab Sally. SF Line and Rederi AB Slite then continued operating Viking Line without Rederi Ab Sally.

Rederi AB Slite went bankrupt in 1993, so SF Line became the only remaining company in Viking Line. SF Line later changed its name to Viking Line.