The contents of this article are non-canon to the Avatar franchise (source).
The Floating Cave is a tall cavern in the Highcrags which the RDA exploited for its unobtanium deposits. They used explosives and built an extensive facility near the top. On the summit, there is a lone willow tree.
Avatar: The Game[]
Nok travelled the height of the cavern during his travels in the Highcrags. He talked to Dr. Ossman at the top and defeated a Digger with help of his prolemuris helper.