This page contains information regarding Star Trek: Lower Decks, and thus may contain spoilers.
No'Mat, or the Caves of No'Mat, was a location in the southern hemisphere of the planet Qo'noS. This icy mountainous location was known for its lava caves. These caves played a role in the Rite of MajQa wherein a young Klingon while meditating would experience a vision. This vision, or hallucination depending upon one's interpretation, might play a role in the Klingon's future. (TNG: "Birthright, Part I", "Rightful Heir"; DS9: "The Sword of Kahless"; DIS: "The War Without, The War Within")
When Worf was young, he ran away to the Caves of No'Mat and had a vision of Kahless, and was told that he'd do something no other Klingon had ever done. Years later, when "Kahless" returned on Boreth, Worf was convinced that he was the real Kahless when he narrated his appearance and words he had said to the young Worf. (TNG: "Rightful Heir")
Ensign D'Vana Tendi's favorite Klingon acid punk song was about the Caves of No'Mat. When she described it to Beckett Mariner in 2381, Mariner remarked, "acid punkers love singing about caves." (LD: "We'll Always Have Tom Paris")
|Geographical features on Qo'noS|
|Land formations: Caves of Kahless • Hamar Mountains • Kang's Summit • Ketha lowlands • Kri'stak volcano • Caves of No'Mat • Lake of Lusor • River Skral|
|Regions: Central Plains Area • Ketha Province • Mekro'vak region|
|Landmarks: Great Domes of Qo'noS • Great Hall/Klingon High Council Chamber • Hall of Heroes • Klingon nightclub • Three Turn Bridge|
|Settlements: Bar'or Lhess • First City/Old Quarter • H'Vek Tar • Ha'r Kling Jaa • Kl'alath • L'chorta • L'vln Lak Raal • Lhess Taal Dax • Lyn'Knor Tak • Mor'em Cha • Qam-Chee • Quin'lat • T'Val K'rang • Tong Vey • V'hechess • Unnamed|
|Other: B'ror Tulvac • B'thel Krang Cha • Ba'Har Tor • Bar' Dak • Br' bethtik • Har'Doth • Hess Kl'gar • K'tang mar • K'ull Tan Saq • Kalax • Khell Tas So • L'Har Mo'Tuk • L'Raal • Moog Kal Chack • Pen'la Took • Qo'har dess • Qo'nVas Tem • Ren Sim'dhal • T'chuu Nak • T'Voq Har • Tar' Kl'val • V'char Tem • Vi'chak • Vort Kling Tuuk|
"The Sword of Kahless" implies that the home of Worf's family was by the mountains containing the caves.
According to Star Trek: Star Charts (pp. 61, 62; "United Federation of Planets IV") and Stellar Cartography: The Starfleet Reference Library ("Federation Historical Highlights, 2161-2385”), there was a star system named No'Mat (Omicron Leonis), in which this planet might possibly have been located, in the Beta Quadrant. This system was located in Klingon space, in the Beta Quadrant.
The Star Trek Encyclopedia (4th ed., vol. 2, p. 84) also stated that No'Mat was a planet.
According to the script for "Birthright, Part I", this location's name was pronounced as "no-MAT".