Boca do Inferno

Boca do Inferno, literally “Mouth of Hell”, is a natural coastal formation west of central Cascais. It consists of a large open chasm connected to the Atlantic Ocean through a natural rock arch. The formation began as a sea cave excavated by waves and chemical erosion in the coastal limestone. As the cavity expanded, part of the cave roof collapsed, leaving the open depression and surviving arch visible today. The surrounding geological formations belong to a coastal sequence containing rocks approximately 150 million years old.

The name derives from the behaviour of the Atlantic inside the narrow opening. Waves entering the cavity are compressed against the surrounding rock and can produce powerful spray and a loud impact, particularly during rough weather. Continued erosion has enlarged the opening and shaped the steep cliffs surrounding it. Boca do Inferno has consequently become one of the best-known geological landmarks on the Cascais coastline.

The site also has an early connection with Portuguese cinema. In 1896, British cameraman Henry W. Short filmed the waves at Boca do Inferno. His short film, A Boca do Inferno, was shown at the Colyseu de Lisboa on 29 September 1896 and belongs to the earliest period of moving-image exhibition in Portugal.

Boca do Inferno became connected with one of the most unusual episodes in the life of British occultist Aleister Crowley in 1930. Crowley, a famous English occultist, ceremonial magician, and writer who founded the spiritual philosophy of Thelema. Often called "the wickedest man in the world," and this one is truly wicked. Crowley had begun corresponding with Portuguese poet Fernando Pessoa in 1929 after Pessoa corrected details in Crowley’s published horoscope. Crowley travelled to Portugal with his German companion Hanni Jaeger, arriving in Lisbon on 2 September 1930, and met Pessoa during his stay.

Following a serious dispute between Crowley and Jaeger, Crowley decided to stage his own death. On 23 September 1930, a supposed suicide was arranged at Boca do Inferno with the cooperation of Pessoa and his friend, journalist and writer Augusto Ferreira Gomes. A farewell message addressed to Jaeger and objects associated with Crowley were used to suggest that he had thrown himself from the cliffs into the sea. The note stated that he could not live without her and made a deliberate play on the name Boca do Inferno, comparing the “other mouth of hell” with Jaeger.

Ferreira Gomes reported the apparent disappearance to the press, while Pessoa helped interpret the occult references contained in Crowley’s note. Portuguese newspapers subsequently reported the supposed suicide, and the police investigated the disappearance. Crowley had in fact secretly left Portugal and later reappeared alive in Germany. The episode was therefore a deliberate hoax rather than an attempted suicide.

Pessoa continued the deception beyond the initial newspaper reports. On 5 October 1930, Notícias Ilustrado published a fabricated interview by Ferreira Gomes in which Pessoa discussed Crowley’s disappearance. Pessoa also began developing the incident into an English-language detective story titled The Mouth of Hell, involving an investigator attempting to determine what had happened to Crowley, although the work was never completed.

The Crowley episode is commemorated at Boca do Inferno by a plaque reproducing the substance of the supposed suicide message. The location therefore combines a distinctive geological formation with a documented episode involving two important figures in 20th-century occult and literary history.