The name 'Devil’s Mouth' originates from the thunderous, growling sound produced when waves compress air inside the cave during high tide.
The site was featured in the 1929 British-Portuguese silent film 'The Man Who Turned to Stone'.
It is a renowned location for observing wave diffraction caused by the specific underwater geometry of the cliff base.
The limestone cliffs in this area are part of the upper Jurassic geological formation.
The site served as a filming location for the 1969 James Bond movie 'On Her Majesty's Secret Service'.
Boca do Inferno is a natural chasm in the limestone cliffs of the Cascais coastline, created by centuries of Atlantic wave erosion. The site features an open cave formation where high-pressure waves surge through a sub-surface tunnel and blast spray upward. It is located on the Atlantic coast of Portugal, serving as a primary geological landmark of the Estoril and Cascais region. The structure consists of a collapsed cavern roof, allowing visitors to view the sea churning within the rock walls. Salt spray and erosion have significantly carved the surrounding jagged shoreline. The site remains a public coastal feature with integrated viewing platforms for safety. It is a prominent example of marine karst erosion on the Iberian Peninsula.
The main viewing railing directly facing the cave mouth, offering a clear view of the water surge.
Visit during high tide to experience the maximum sound and water spray intensity.
Bring a windbreaker or protective gear, as sea spray frequently reaches the observation platforms.
Stay behind the safety fences at all times, as the limestone edges can be unstable and slippery.
Attempting to climb down into the cave or onto the unprotected cliff ledges, which are prone to sudden erosion and high-tide surges.
Wear non-slip footwear suitable for wet, uneven stone surfaces.
