The best independent guide to Cascais
The best independent guide to Cascais
The Boca do Inferno is a unique sea arch and cliff formation along the Costa da Guia, to the northwest of Cascais.
This coastline comprises high eroded limestone cliffs that are relentlessly battered by the full force of the Atlantic Ocean. At the Boca do Inferno, the slightly acidic rainwater has eroded a weaker limestone vein. It was originally a sea cave that subsequently collapsed, leaving a chasm and sea arch.
Into this opening, the powerful Atlantic waves continually crash, and during violent winter storms, water explodes upwards, similar to an erupting volcano—hence the overdramatic name of Boca do Inferno (Hell's Mouth).
The sea arch and chasm of the Boca do Inferno on a calm summer day
The Costa da Guia and Boca do Inferno are highly recommended to visit during your trip to Cascais. Here giant waves pound the cliffs, while at high tide, waves roar through the arch into the base of the chasm.
Situated at the Boca do Inferno is a viewing platform, an excellent seafood restaurant (Mar do Inferno), and the Mercadinho Boca do Inferno, a handicraft market selling regional gifts.
If you are on holiday to Cascais, the best time to visit is at sunset, when the sun sinks below the ocean, and the sky is illuminated in orange glows – simply magical.
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Ferocious winter waves crashing through the sea arch
Seaward entrance to the Boca do Inferno as seen from the cliffside viewpoint.
The Boca do Inferno is free to visit, and there is no entrance fee for the viewing platform. It should be noted that the Boca do Inferno is only a minor tourist attraction of Cascais, and is often used as the end point of a short walk from the centre of Cascais. A typical visit is 20 minutes, but if you are visiting as part of an organised tour, 10 minutes is sufficient to see the cliffs and sea arch.
The Boca do Inferno is best seen on a stormy winter's day, when the waves crash through the sea arch – on a calm summer's day, the whole experience may be a bit tame.
During the winter or in storms, the viewpoint may be closed. Even in good weather, the cliffs can be dangerous, and there have been many occasions when people have been swept off or slipped down the perilous cliffs.
Insight: Sometimes visitors new to Cascais mix up the Boca do Inferno with the Cabo da Roca, which is the most westerly point of Mainland Europe and is 13km to the north.
The viewing platform is a magical location to watch the sunset out across the Atlantic Ocean
The Boca do Inferno lies 2km to the west of Cascais and is a popular 20-minute walk from the centre of the town.
The best route follows the coastal road (the Avenue Rei Humberto Ii de Itália) westwards out of Cascais, and passes the Condes de Castro Guimarães Museum and Santa Marta Museum. This route to the Boca do Inferno follows a cycle path (clearly marked in red), and hiring a bike to cycle here is an alternative option.
A taxi from the train station would cost between €7 and €9, but finding a return taxi may be challenging. The same ride would cost €4-5 by Uber or Bolt.
While the waves are calm, the Cascais cliffs are a favourite location for fishing.
Warning: While at the Boca do Inferno, you will see locals fishing at the very edge of the cliffs, do not follow their example, these cliffs are very dangerous.
Close to the Boca do Inferno is the Mercadinho Boca do Inferno, a series of market stalls that sell local handicrafts and gifts. This is a great location to purchase gifts and traditional Portuguese products, and it tends to be cheaper than the tourist shops in central of Cascais.
The handicraft stalls of the Mercadinho Boca do Inferno
There is a selection of cafes and kiosks at the Boca do Inferno, but the stand-out one is the excellent Restaurante Mar do Inferno, a restaurant that specialises in seafood and has a romantic sea view setting. Their menu can be seen on their website:
For a less expensive meal option, consider the café next door, the Rocha do Inferno, which has been run by the same family for over 80 years.
The Mar do Inferno restaurant.
The gnarled and jagged cliffs of the Costa da Guia are formed from limestone, which is very resistant to the powerful ocean. They are eroded into their strange shapes by rainwater, which is slightly acidic due to the dissolved carbon dioxide. Over millennia, this acidic rainwater dissolves the limestone.
The Boca do Inferno was formed by the erosion of a weak vein of limestone in the cliff face, creating a large sea cave. The more resistant outer rock remained while the weaker rock was eroded to such a stage that the roof of the cave collapsed, forming the Boca do Inferno.
During the winter, the waves crash into the Costa da Guia coastline
The interior of the opening has been eroded in differing rates
In 1930, Aleister Crowley, a magician, astrologer, and mystic, faked his own death at the Boca do Inferno in Cascais. As part of the stunt, he secretly left Portugal to reappear 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 helped to promote his work.