During Roman times, the grotto was used as the personal swimming hole of Emperor Tiberius as well as a marine temple. Tiberius moved from the Roman capital to the island of Capri in 27 AD. During Tiberius’ reign, the grotto was decorated with several statues as well as resting areas around the edge of the cave.
During the 18th century, the grotto was known to the locals as Gradola, after the nearby landing place of Gradola. It was avoided by sailors and islanders because it was said to be inhabited by witches and monsters. The grotto was then “rediscovered” by the public in 1826, with the visit of German writer August Kopisch and his friend Ernst Fries, who were taken to the grotto by local fisherman Angelo Ferraro.
The Blue Grotto is 60 meters long by 25 meters wide. The clear blue waters below the boat are 150 meters deep. The unearthly blue light effect is caused by the refraction of daylight through the above water cave opening and a larger submerged opening. The acoustics inside the grotto are famously beautiful. At the back of the main cave, three connecting branches lead to the Sala dei Nomi, or “room of names”, named after the graffiti signatures left by visitors over the centuries. Two more passages lead deeper into the island, before it becomes inaccessible. For many years it was thought that the fissures at the back of the cave may have been ancient stairways leading up to the Emperor’s pleasure palaces, but it now seems that these are merely natural passages which narrow and then end, no palace in sight.
Three statues of the sea gods Neptune and Triton were recovered from the grotto floor in 1964 (now on display at a museum in Anacapri), and seven statue bases were found in 2009. The Roman historian Pliny the Elder described the statues in the grotto as “playing on a shell” – the position of the now missing arms of the Triton statue, usually depicted with a conch shell, indicate that these were the statues that he saw in the 1st century AD. Four more statues may yet be hidden in the sandy depths.