The Rhinessa system is a trinary star system located in the Beta Quadrant in the proximity of the Typhon Expanse and Starbase Expanse 7. It consists of 18 planets, 8 of which are Class J, 2 Class K, and 1 Class L. None of the planets were habitable.
In 2372, the USS Cantabrian followed Yh'ahni and the trader Wenloth to the Rhinessa system to free Starfleet officers and Federation civilians being held by the Myhr'an at the Myhr'an internment camp on Rhinessa VI. The Cantabrian was successful in rescuing the majority, and, with the USS Aotearoa, destroyed one Myhr'an battle cruiser and the internment camp as well as severely damaging two other Myhr'an battle cruisers, before they fled the system. (Star Trek: The Cantabrian Expeditions: "Two Hit, One Stone")