This cave is known as "Blue Grotto".
The water inside it emits blue light as soon as sunlight hit the water.And another amazing thing is that anything immersed in water appears silver,due to bubbles in the water.
This cave is the sea cave that is on the coast of the island of the Capri,southern Italy.
It was believed that in Roman Period the cave was the home of nereids, sirens, and devils.
the pictures are from http://www.capri.com/en/s/la-grotta-azzurra
http://www.shoreexcursionsgroup.com/tour/blue-grotto-marsaxlokk-malta/EUMLAGLBGRMLK
http://all-that-is-interesting.com/blue-grotto
