The Huygen Cluster was a region of space, a star cluster located in the galaxy's Alpha or Beta Quadrant.
History and specifics[]
The cluster contained an apparent wormhole that actually was the entrance to a pocket universe.
In 2270, while charting the cluster, the Federation starship USS Enterprise discovered the pocket universe and sent a landing party aboard Columbus to investigate. The shuttle was destroyed, but Nyota Uhura discovered a unique lifeform within. She was able to transmit transporter coordinates to the Enterprise so they could be rescued. (TOS - Unlimited comic: "Message in a Bottle")