Boca do Inferno ( Portuguese for Hell's Mouth) is a

chasm In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-graben wi ...

located in the seaside cliffs close to the Portuguese city of

Cascais Cascais () is a town and municipality in the Lisbon District of Portugal, located on the Portuguese Riviera. The municipality has a total of 214,158 inhabitants in an area of 97.40 km2. Cascais is an important tourist destination. Its marin ...

, in the District of Lisbon. The seawater has access to the deep bottom of the chasm and vigorously strikes its rocky walls, making it a popular tourist attraction. The cave was the first to be depicted in moving pictures, in the 1896 British film '' A Sea Cave Near Lisbon'', which shows waves breaking at the mouth of the cave.

References

{{Lisbon-geo-stub Geology of Portugal Cascais e Estoril