In 1948, Rederi Ab Vasa-Umeå was founded to start passenger traffic across Kvarken, the narrowest part of the Gulf of Bothnia.

In 1958, Merivienti Oy, subsidiary of the Finnish forest industry giant Enso-Gutzeit, became the largest owner of Rederi Ab Vasa-Umeå.

In 1976, Vaasa-Umeå purchased MS Viking 3 from Rederi Ab Sally, and reused the name Wasa Express for her.

Enso-Gutzeit became the sole owner of Vaasa-Umeå in 1979, and changed the company's name to Vaasanlaivat – Vasabåtarna (The Vaasa Boats).

In 1981, the company chartered MS Wasa Star from Rederi AB Gotland, bringing the first large ferry to the Gulf of Bothnia.

In 1982 Enso-Gutzeit decided to bow out of the shipping business, and Vaasanlaivat was sold to Rederi Ab Sally (most of their other operations passed to Effoa).

A part of the payment was made in the form of MS Fenno Express, a small ship better suited for Jakob Lines' traffic.

[1] The company acquired the rights to the Wasaline brand from RG Line and started operations with the ferry Wasa Express.

Over the next years, Wasaline established itself as a reliable and valuable cargo carrier between Finland and Sweden and passenger numbers began rising once again.