Hells Mouth is an interesting cliff formation close to Cascais, which has been given an overly dramatic name of Hell’s Mouth. The ceaseless pounding of the Atlantic Ocean on the cliffs chiselled out a small cave, which subsequently collapsed forming a small bay and natural arch.

In the summer these waves merely splash around in the open cave but during winter storms the full force of the ocean is funnelled into chasm which gives rise to the the name of the rock formation. Boca do Inferno is a popular excursion from Cascais, commonly as a short walk or bike ride. At Hell’s Mouth there are pathways allowing tourists to climb down the cliff face and view the unique formation from both sides.

The Boca de Inferno lies 1.5 km to the west of Cascais and is a popular walk from the centre of the town. To reach it follow the Avenue Rei Humberto Ii de Itália past Cascais Marina and along the coastline. This road also has one of the only cycle paths in Portugal. There is no entrance fee to visit the Boca do Inferno and the site is open all the time.

Close to the Boca do Inferno Cascais are a set of small market stalls which sell the best value tourist gifts in Cascais. The walk to the Boca do Inferno takes around 40 minutes and most visitors spend 30 minutes watching the waves smash against the cliffs or clambering over the rocks. To fully appreciate why the open cave is called Hell’s Mouth sneak a look at the postcards on sale at the gift shops.
The Boca do Inferno was formed by the erosion of a weak vein of limestone in the cliff face. This initially lead to a cave being excavated which slowly expanded over the generations. The tougher outer rock remained while the weaker rock was eroded to such a stage that the roof of the cave collapsed forming the unique Boca do Inferno.
In 1930 Aleister Crowley an magician, astrologer and mystic faked his own death at the Boca do Inferno Cascais. As part of the stunt he secretly left Portugal to reappeared three weeks later at an exhibition of his work in Berlin. The whole controversy was wildly and excitedly reported in the newspapers of the era and help to promote his work.

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