[2][3] Calypso was based at the Washington Navy Yard as a tender to her sister ship, the presidential yacht Potomac.

In this capacity, her operations were confined largely to the Potomac River and Chesapeake Bay until 22 July 1941, when she put out for a cruise to Nova Scotia.

During a portion of this cruise she had on board President Franklin D. Roosevelt, bound for the famous Atlantic Conference in Argentia Bay, Newfoundland, with Prime Minister Winston Churchill of the United Kingdom.

On 15 September 1943 she rescued 60 sailors from the torpedoed patrol vessel USS Plymouth despite heavy seas and sharks.

[5] In 1955, Calypso was acquired by Circle Line Sightseeing Cruises of Manhattan, New York and converted into a tour boat.