The Blue Grotto or Blue Cave (Croatian: Modra špilja), is a water-logged sea cave located in a small bay called Balun (Ball in the local dialect), on the east side of the island of Biševo and about 4.5 nautical miles (8.3 km) from Komiža, in the Croatian Adriatic. It is situated in the central Dalmatian archipelago, 5 km south-west of the island of Vis.