While the Playboy mansion’s infamous grotto might get the most attention in the pop cultural realm, natural grottos off the coast of Italy (and around the world) are a source of wonder for millions and a major tourist hotspot. Italy’s Blue Grotto and Emerald Grotto are natural sea caves that illuminate seawater with a mystical glow with either bright blue or deep green hues, respectively. This natural light filtration creates otherworldly tones that look anything but ordinary.
The Blue Grotto is located close to Capri, a small island off the coast of southern Italy. Thousands of visitors make their way to the cave each year, hoping to be wowed by the grotto’s mystical blue water. There are two sources of light in the Blue Grotto, a small hole and meter-and-a-half wide opening that is used as the cave’s entrance. Together, these light sources give the water its characteristic cerulean “glow.”