Gheryzan was a locale in Trill's eastern hemisphere. It was the location of Gheryzan Hospital, which housed Trill's long-term mental health facilities. (DS9 short story: "Reflections")

the planet Trillius Prime
cities and settlements	B'tar • Chi'tar • Gheryzan • Iklan • Kural • Leran Manev • Mak'ala • Murona • Shator • Tear'c • Vor'lan • Vrans
landmarks and geography	Ayai'leh-hirh (Mount Arken • Ilrienh • Noraikghe • Oraidhe • Sethe) • Caves of Mak'ala • Deln Mountains • Devritane Museum • Dorabi subcontinent • Dorvan mines • Ganses Peninsula • Hoobishan Baths • Irnek Peninsula • Kem'alta Institute • Korchub Mountains • Lekarna Mountains • Manevri • Najana Library • Nalep Mountains • Tash Mountains • Tenar • Tenara (Tenaran Ice Cliffs • Tenaran Music Academy) • Thorain Mountains • Trill Senate Tower • Urot Mountains • Venar Mountains
bodies of water	Aldar Bay • Dara'air Ocean • Lake Ograls • Manev Bay • Sea of Arlibath • Troyval Ocean • Turek Sea • Uzonn Ocean