Situated on the east side of the island Biševo in the cove Balun, 4.5 nautical miles (8.3 km) off Komiža. It is one of the most popular natural monuments of the Adriatic. It is 10-12 m wide and 24 m long. It was discovered by Baron Eugen von Ransonet in 1884 and has been open for public ever since.
The cave can be entered in a small boat through a narrow, 1.5 m high and 2.4 m wide entrance. The sunlight enters through an underwater passage, reflects itself off the ground and provides an amazing blue-silverish glimmer. Depending on the time of the year, the best time for the visit to the cave is between 10 am and 2 pm. About 50 000 visitors come to see the cave every year.