The Grotta dello Smeraldo received its name for its water's unique emerald glow. The entrance to the grotto lies slightly below the water. It's the sunlight that is refracted through the underwater opening that produces the bright emerald color throughout the cave.
Visitors can actually access the small grotto from a parking lot just off the Amalfi Coast's main highway (Strada Statale 163). For a fee, an elevator in the parking lot will take visitors down to the grotto and tour boats will give a quick ride around the cave.
Photo by GothEric/Flickr