Modra spilja (The Blue Cave), located in a small cove of Balun on the island of Biševo. The cave itself is 24 meters long, 10–12 meters deep and up to 15 meters high, while the entrance to it measures 1.5 meters high and 2.5 meters wide.

In the year 1884. baron Eugene von Ransonnet described and depicted it. On his suggestion the entrance to the cave has been enlarged, thus making it accessible to the entire world. The cave has two entrances: the smaller one artificially widened and deepened so that the boat could sail through, and the wider one, located at the southern part of the cave - the underwater passage, through which the magical game of the light and water is performed...

Depending on the season, the ideal moment to visit the cave is between 9 and 13 o’clock in the morning.