Melissani Cave

Melissani Cave or Melissani Lake, also Melisani is a cave located on the island of Kefalonia, northwest of Sami, about 5 km Southeast of Agia Effimia, Northeast of Argostoli and Northwest of Poros. The Ionian Sea lies to the east with the Strait of Ithaca. Forests surround the cave and the mountain slope is to the west. Near the cave is the entry to the cave with parking lots and is passed almost in the middle of the main road linking Sami and Agia Efimia especially to the northern part of the island. Some say the water is so clear the boats look like they are floating on air.

Source: Wikipedia