Nestled in a cave that overlooks the Adriatic Sea in the South of Italy lies one of the world's most romantic restaurants: the Grotta Palazzese. It's exactly where you'd expect to find one too.

Visitors can take a rowboat or a private tour to discover this cave where the water turns a glittering emerald hue in the sunlight. A few miles from Amalfi, the Grotta dello Smeraldo (Emerald Cave ...