Legend has it that once a vulture swallowed a pen-knife by accident while feeding on a dead animal.  The vulture suffered days with the metal inside. A holy man meditating nearby witnessed this but had no ways to help the bird.  One day, the man saw the vulture drinking water from a cave and eventually getting better within a few weeks. The old man found the cave water hot and smelly. He drank the water and soaked in it. He too became healthier and happier. Thus the hot springs were introduced to mankind. For a Bhutanese visiting hot springs is a wellness therapy.