Mount Roraima, South America
This tabletop mountain is one of the oldest mountains on Earth, dating back two billion years when the land was lifted high above the ground by tectonic activity. The sides of the mountain are sheer vertical cliffs, with several waterfalls, making it nearly impossible to climb.
Sadly, the mining company that owns the caves could no longer afford to keep the massive pumps going to clear the chamber. I believe the pumps were shut down a few years ago and the cavern is refilled with water. The crystals are growing once again, but no one will ever see it.