Boca do Inferno ("Hell's Mouth") is located in the seaside cliffs close to Cascais, in the metropolitan area of Lisbon. It is just 50 minutes away from Portugal's capital.

This breathtaking viewpoint is an unique geological formation and a world-renowned tourist attraction. Originally, this used to be a giant cave, but throughout the centuries, the natural erosion caused by the waves and the rain made its "ceiling" collapse at some point, resulting in Boca do Inferno as it is today.