The Blue Grotto (Grotta Azzurra) is a noted sea cave on the coast of the island of Capri, Italy. Sunlight, passing through an underwater cavity and shining through the seawater, creates a blue reflection that illuminates the cavern.
The beauty of the Blue Grotto was described in 1826 by the German writer August Kopisch. Since then the Blue Grotto has become the emblem of the island of Capri. The grotto was known by the Romans, as proved by the antique statues which were found in the Grotto. This discovery, the remains of an ancient landing place and the work on an underground tunnel, create an image of a natural cavern adorned by statues. The grotto was known to the locals under the name of Gradola, after the nearby landing place of Gradola, but it was avoided because it was said to be inhabited by witches and monsters. The Blue Grotto was used by the emperor Tiberius as his private swimming pool.