The Blue Grotto (Italian: Grotta Azzurra) is a sea cave on the coast of the island of Capri, southern Italy.

The oarsman then uses a metal chain attached to the cave walls to guide the boat inside the grotto.

The quality and nature of the color in each is determined by its unique combination of depth, breadth, water clarity, and light source.

In the case of the Blue Grotto, the light comes from two sources: the narrow arched entranceway, and a large hole somewhere below the above water entrance, separated by a band of rock between one and two meters tall.

Because it is farther from the surface much less light passes through the lower opening, but its depth and size allow it to be the grotto water's primary source of illumination.

Three statues of the Roman sea gods Neptune and Triton were recovered from the floor of the grotto in 1964 and are now on display at a museum in Anacapri.

Two priests determined to drive them away entered the cave swimming, after a few minutes spent inside it they ran away in panic as if they had seen the face of the devil.

In this fantastic tale, Golfo, the demon who rules the Blue Grotto, transforms the ballet's heroine, Teresina, into a Naiad.

Mark Twain visited the Blue Grotto in 1867 and recorded his thoughts in his book The Innocents Abroad.

In Alberto Moravia's 1954 novel Il disprezzo (Contempt), a vision appears to the protagonist when, under heavy mental stress, he visits the cave alone.