No'Mat
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. (; ; )

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 "" 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. ()

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." ()

Background Information
 implies that the home of Worf's family was by the mountains containing the caves.

The draft script for  had an extra line where Torin said Worf had told him of his vision of Kahless. Torin decided to imprint that memory in order to get Worf to believe. 

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 (), 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  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". 

de:Höhlen von No'Mat
nl:No'Mat
Qo'noS
Geography