Calypso

The Calypso was a Federation captain's yacht that was in service with Starfleet in the mid-24th century, attached to starships, among others the USS Enterprise (NCC-1701-D). (Star Trek: The Next Generation)

Background
The captain's yacht was the brainchild of Andrew Probert when he beefed out the details of his Galaxy-class design. Probert postulated, "''In the original show the dome on the bottom of the ship was a sensor array. What I did was move the sensor array to more of a surrounding detail, leaving the dome on the bottom free. That's where I put the captain's yacht, which is a private vessel for dignitaries and captains of ships to use as personal shuttles. That was never used in the show. At one point there was a script where Picard was returning to the ship and the dialogue was, "The captain's shuttle is on the way back. Crew members, man your stations." Then the captain comes aboard. We never ever have a visual, so I suggested mentioning the yacht, but they decided against it.''" (, p. 55)

Though never stated in the canon, it was almost certain that this vehicle was abandoned with the saucer section of the Enterprise-D on the surface of Veridian III.

Captain's Yachts did not become part of Trek canon until the debut of the USS Enterprise (NCC-1701-E)'s Cousteau in.

Star Trek: The Next Generation Technical Manual
The Calypso was never seen in use or mentioned in dialog, but its designation came from the Star Trek: The Next Generation Technical Manual. It was named for Jacques-Yves Cousteau's ship  by Patrick Stewart. Production staff wanted to use the yacht in episodes such as and, but budget restrictions prohibited building a miniature and sets.

Authors Rick Sternbach and Michael Okuda delved somewhat deeper into the specifics of the Calypso when upgrading their writings for the much (color) enhanced 1992 Impel trading cards set, Star Trek: The Next Generation - Inaugural Edition (card 111).

Apocrypha
The reference work Star Trek: Starship Spotter categorized the Calypso as a Mark I Captain's Yacht.