The Blue Grotto is a marine cave located on the coast of the island of Capri in southern Italy. The cave is 60 meters long, 25 meters wide, and extends about 150 meters deep under the sea. The cave is considered one of the picturesque natural wonders of Capri, as the sunlight that passes under the water cavity creates a blue reflection that shines The cave is from the inside, and the cave has been provided with modern lighting techniques that increase the intensity of the blue radiation in it. Visitors can enter the cave through small boats and use metal chains attached to the cave walls to guide the boat inside the cave.