MS Estonia was an Estonian cruise ferry built at Meyer Werft Shipyard in Papenburg, Germany, in 1980. The vessel’s previous names were Viking Sally (1980–1990), Silja Star (1990–1991) and Wasa King. The Estonian Shipping Company and Nordström & Thulin bought her for Estline's Tallinn-Stockholm line. The MS Estonia commenced traffic under the Estonian flag on February 2, 1993. The Finnish shipping company Rederi Ab Slite ordered her under Viking Line’s trademark, and her first name was Viking Sally. The vessel was 155,43 m long and 24,21 m wide, with max possible speed of 21 knots. There were 1,190 cabin beds, and two car decks had room for 460 vehicles.

On June 29, 1980 the vessel made her first journey on the route Turu–Mariehamn–Stockholm. She was sold to Oy Silja Line Ab in 1990 and christened as Silja Star.
In the same year it was decided to sell the vessel once again and she was owned by Wasa Line, which belonged to Silja Line's proprietor EffJohn International. Her name was changed to Wasa King. Estonians started to show their interest in the vessel in 1992. Under the  Estonia Shipping Company that was registered in Cyprus and that bought the ship, there were actually two big companies - Nordström & Thulin from Sweden and the state-owned company Estonian Shipping Company. After a long consideration the ship got a new name - MS Estonia. The last owners introduced a new line Tallinn–Stockholm.

On the night of September 28, 1994, going from Tallinn to Stockholm, MS Estonia sank and 852 people drowned.