Fire Caves
The Fire Caves on Bajor were a prison created by the Prophets to contain the Pah-wraiths after they attempted to seize the Celestial Temple. Despite the name, there was never any actual fire in the Caves except when the Pah-wraiths were nearly released.

During the Occupation, the Cardassians found the Bajorans' fear of the Caves to be amusing, but they never explored them. ()

Benjamin Sisko wanted to visit the Fire Caves in 2369 with his son Jake Sisko, after attending the Gratitude Festival. ()

Keiko O'Brien visited the Caves during an expedition in 2373, and unwillingly became host to one of the Pah-wraiths until it could be forced out by her husband Miles. ()

In late 2375, Kai Winn Adami and Dukat attempted to free the Pah-wraiths from the Caves, using the Book of the Kosst Amojan. Winn was initially concerned about releasing them, as Bajoran prophecy stated their release would mean the end of Bajor. ()

One of the wraiths did escape and joined and reanimated the dead Dukat who then prepared to release the others. Dukat's ego however not only prevented him from killing Sisko at once but allowed him to gloat over Kai Winn's death. The slight distraction gave the Emissary/Benjamin Sisko the time he needed to throw himself, the book and Dukat in to the fire below, destroying the book and therefore trapping Dukat with the Pah-wraiths forever. ()

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Bajor
Geography