MS Saga Ruby is a cruise ship owned and operated by Saga Cruises. She was built as the combined ocean liner/cruise ship MS Vistafjord in 1973 by Swan Hunter Shipbuilders in the United Kingdom for the Norwegian America Line. In 1983 she was sold to Cunard Line, retaining her original name until 1999 when she was renamed RMS Caronia. In 2004 she was sold to her current owners.
The Vistafjord was ordered by Norwegian America Line (NAL) from Swan Hunter Shipbuilders, Newcastle, United Kingdom. She was based on the company's 1965-built MS Sagafjord, but with an enlarged hull, additional superstructure deck and improved interior layout. However, as the cost of building the Sagafjord had put her builders, Forges et Chantiers de la Mediterranee, out of business, the Vistafjord had to be built at a different shipyard. She was launched on 15 May 1972 and delivered to the Norwegian America Line exactly a year later on 15 May 1973. She is the last cruise ship to have been built in the United Kingdom.