Legend has it that many years ago there was a very bad man with a very bad temper called Pêro Botelho who lived in Furnas.
Now, the people of this place used the Caldeira das Chãs, or as they called it, the Boca do Inferno, to cook food, due to the geothermal activity of the place. On the other hand, people collected the mud that surrounded the caldeira because it had healing effects. But to do this, one had to get dangerously close to the mouth of the boiler.
Then, one day, Pêro Botelho, trying to collect this mud slipped, fell into the boiler and was never seen again.
The people believed that Pêro Botelho, being the terrible man he was, was pulled by the devil himself into the boiler, then nicknamed “Hell’s mouth”.
So people, whenever they used the boiler or passed by it, called Pêro’s name, receiving in response a strong blast of sulfur and stone from inside the boiler.
Believing that this was certainly the work of the man who had fallen in, the people started calling the place Caldeira de Pêro Botelho, saying that he was still there.