The Barzan wormhole was a wormhole which had one terminus near the Barzan homeworld in the Alpha Quadrant and another that was unstable in the Delta Quadrant. The Cardassians knew about or suspected the existence of the wormhole more than a decade before its discovery. Elim Garak studied it while he was at the Bamarren Institute for State Intelligence. (DS9 novel: A Stitch in Time) In 2373, the two Ferengi were found by the USS Voyager and tried to escape back through the wormhole. They made both ends of the wormhole unstable in their attempt. (VOY episode: "False Profits")