According to newspaper Correio da Manhã (CM), the unchartered hole had been covered by vegetation and was discovered by mistake as parish employees cleared the area of rubbish. It was discovered around two weeks ago.

The grotto is estimated to measure five metres in diameter and ten in depth and is sparking curiosity among both tourists and local residents.
Local Parish Mayor Luís Bentes told CM: “Its diameter was smaller when we uncovered it two weeks ago, but the rain caused a chunk to fall off and now another part has collapsed.”
The area has been taped off until authorities have a better look at the discovery.
Some locals believe the cave is man-made and could unearth more details about local history.
Luís Bentes also said a number of tunnels exist in the area, which could lead to the cliff-top Senhora da Rocha Hermitage, and that a fortress and a medieval castle also existed in the area many moons ago.
A spokesperson for the APA – Portuguese Environment Agency told CM initial indications are that the grotto is a “natural” cave, but it is being looked in to.