Ultima Thule was a planet, where a dolamide purification plant was located. Ultima Thule was the last stop on the route taken by Valerian traders supplying weapons-grade dolamide to the Cardassians.

The Valerian transport Sherval Das visited Ultima Thule in 2369 a week prior to docking at Deep Space 9, suggesting that they were carrying dolamide. (DS9: "Dramatis Personae")