Boca do Inferno

Dramatic sea cave and cliff arch near Cascais where Atlantic waves thunder into a narrow chasm — a spectacle with a dark legend.

"Mouth of Hell" lives up to its name. Boca do Inferno is a dramatic natural arch and sea cave in the limestone cliffs just outside Cascais, where Atlantic waves funnel into a narrow chasm and explode upwards in spectacular spray when the swell is running. An easy coastal walk from Cascais town centre leads to the clifftop viewpoint. The place carries a whiff of the uncanny: in 1930, occultist Aleister Crowley staged his own death here as a publicity stunt — and reappeared alive a few weeks later. Today it attracts day-trippers, photographers, and anyone craving the raw, elemental force of the Atlantic at close quarters.