Deep Space 3 was a Federation space station that was in service with Starfleet in the late 24th century. This starbase was located near a black cluster, and, in 2370, was commanded by Admiral Marcus Holt.
In that year, the station hosted the annual palio, wherein the Ferengi were accused of trying to bribe the Breen pilot into throwing the race.
Later that year, the USS Hera, commanded by Captain Silva La Forge, departed Deep Space 3 on a courier mission and disappeared shortly after. (TNG: "Interface")