What Is Bletonism?
Bletonists are also called water dowsers or diviners. They often use a forked branch of a tree, bent pieces of metal or plastic wire or a small pendulum to indicate when water is present.
There is no scientific evidence that bletonism works or any accepted scientific reason why it should. It's pretty impressive when you see it "working" though. Mumbo-jumbo-meter: 7/10.