A Starfleet transport ship carrying colonists that struck a leftover gravitic mine in 2368 and crashed with heavy casualties, bringing the Enterprise to the rescue in the episode Ethics.
The USS Denver is a Starfleet transport. In 2368 it is carrying more than five hundred colonists when it hits a gravitic mine left behind from the Cardassian war and crashes with great loss of life.
The ship is not seen, but its fate drives part of the episode Ethics. The Enterprise breaks off to help, and its shuttlebays are turned into a triage ward for the survivors.
During the emergency the visiting neurologist Toby Russell gives one of the injured an untested drug, borathium, in place of a standard treatment, and the patient dies. Beverly Crusher relieves her of duty for it, sharpening their dispute over Russell's risky proposal to replace Worf's damaged spine.