Falls of Truth

The, is a waterfall located on the Island Turtle. There, Killer B trained to control the Eight-Tails. The waterfall itself is peculiar in that by sitting on the platform at its base and concentrating, the person is transported into their mind. Once there, the waterfall becomes a mirror which reflects one's true self. This is the first step in the training regime to control the tailed beast. Behind the waterfall itself, there exists a temple where jinchūriki can then take the next step in controlling their beast.

Trivia

 * At least two known jinchūriki have undergone and successfully completed this part of the training: Killer B and Naruto Uzumaki.