- This article is about the cave in which Hama imprisoned her bloodbending victims. For other similar uses, see Prisons (disambiguation).
The mountain prison is a large cave underneath the mountain near the village where Hama once lived. She discovered this cave years before Team Avatar's visit, and during full moons, she would use bloodbending on the innocent Fire Nation civilians living in the village, forcing them to walk into the cave. Before Hama's imprisonment, the only person known to have escaped her clutches was an elderly man named Ding.
While Team Avatar was staying in a forest near Hama's village, Toph heard what she thought were people screaming for help under the mountain, but the theory was dismissed by the rest of Team Avatar as unlikely. Later on, when Katara left with Hama to learn more about waterbending, the others set out to talk to Ding to try to figure out what happened to him. When he said that he was guided to a cavern up the mountain, Toph realized that the missing villagers must have been the source of the screaming she had heard before. Toph located the cave using her seismic sense, and inside, they found the missing villagers held in the prison. They told them that Hama was responsible for their imprisonment. The group realized Katara could be in potential danger, so Aang and Sokka left to save Katara while Toph stayed behind to free the captives.