RMS Caledonia was a British ocean liner built by Alexander Stephen and Sons for the Anchor Line which was converted into an armed merchant cruiser during World War II.

[1] The ship was ordered by the Anchor Line from Alexander Stephen and Sons.

On 3 October 1925, she departed on her maiden voyage on the Glasgow to New York route.

In March 1936 the ship's accommodation was changed from first, second, and third-class to the cabin, tourist, and third class.

[2] In September 1939, the liner was decommissioned from passenger service and requisitioned by the Royal Navy as an armed merchant cruiser and was renamed as HMS Scotstoun.