The Federation starship whose crew found the deactivated android Data on the dead colony world Omicron Theta in 2338 and switched him on.
The USS Tripoli is a Federation starship of the 2330s. It is never seen, but it has an important place in Data's history as told in the episode Datalore.
In 2338 the Tripoli arrives at the colony on Omicron Theta, drawn by a signal, and finds the planet stripped of all life. A landing party discovers Data lying in the open on a rock shelf, with the colonists' knowledge stored in his memory. They activate him, and he later chooses to enter Starfleet in imitation of his rescuers.
When the Enterprise returns to the planet in 2364, Data shows his crewmates the spot. Nearby they find Noonien Soong's hidden laboratory and the parts of Lore, which the Tripoli's crew had missed.