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Observation deck · Cascais, Lisboa
Boca do Inferno
An opening in the cliff west of Cascais, where the sea enters a collapsed cave and, with strong waves, sprays water between the rocks. There are viewpoints and a coastal walkway.
Illustrative images. The pictures in this guide are illustrations based on the real place, not photographs, and may differ from it.
Discover
About Boca do Inferno
Boca do Inferno is a formation on the rocky coast about 2 km west of Cascais town centre. The sea carved a cave into the rock, whose roof collapsed, leaving an opening where the waves enter forcefully.
On rough-sea days, the water hits the walls and sprays upward, with a loud noise that gave the place its name. On calm days, the water is quieter and you can see the bottom of the cavity.
Platforms and viewpoints allow you to see the opening from above. Around it, the dark rocky coast continues west toward the Guincho.
The English writer and occultist Aleister Crowley staged his own disappearance there in 1930, an episode that became part of the place's history.
Before you go
Practical information
Cidade Turismo reviews its information regularly, but something may have changed. Check with the place before planning your trip.
How much time to set aside
20 to 40 minutes.
Best time
On rough-sea days, more common between October and March, the waves are stronger. In the late afternoon, the low light illuminates the rocks.
How to get there
It is located on Avenida Rei Humberto II de Itália, about 2 km from Cascais town centre. Walk along the coastal promenade, go by bike or by bus.
Tip
Stay on the platforms and respect the fences: the rocks become slippery when waves hit. Combine the visit with the Farol de Santa Marta along the way.
Get your questions answered
Frequently asked questions about Boca do Inferno
What is Boca do Inferno?
A cave in the cliff whose roof collapsed, where the waves enter forcefully on rough-sea days.
What's the best time to see the waves?
Days with rough seas, more common between October and March.
Is Boca do Inferno far from the centre?
About 2 km west, on foot along the coast, by bike or by bus.