A black hole propulsion drive was a type of propulsion system that was utilized by an unidentified species, first encountered by Starfleet aboard "The Beast" in 2376. The system works by creating dozens of small quantum singularities and dropping them into subspace. The singularity then returns to normal space a short distance away, which shunts the containment and the ship as well. (SCE eBook: The Belly of the Beast)