The Blue Grotto (Modra Spilja) is located in the small cove of Balun on the island Biševo.
The cave Blue Grotto has two openings, a small artificially deepened, through which you can get in with a boat. The second entry has the shape of an arc and is much more larger then the first one, and is located under the sea level. Through the opening the sunlight penetrates into the cave, which passes through the water filling the entire cave of a silver glow blue. Depending on the season, the best time to visit the cave is between the hours of 9 and 13.