Biševo island: Balun and Mezuporat
Biševo island is the home of the Modra špilja, the Blue Cave in Balun bay on its eastern side. For a visit, the practical place name to know is Mezuporat: the nearby bay where the small concession boats depart. Keeping the cave's location and the boarding bay distinct helps make sense of an excursion itinerary or a scheduled journey from Komiža.
The island is more than a label on a multi-stop boat trip. Its light phenomenon, visitor centre and protected natural setting all form part of understanding the visit. Choose your boat arrangements around what you actually want to do, whether that is an organised cave outing or a separately planned island connection. The transport guide explains the different stages.
Our pick: Boat trip to Biševo
This boat trip offers a visit to Biševo with snorkeling equipment.
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Visit Biševo as part of a boat excursion
The outing visits Biševo through the Blue Cave and includes bottled water and snorkelling equipment for outside stops. Choose it for the boat itinerary, rather than assuming time to cross the island independently.
Sunlight through the underwater entrance
The cave's blue colour is a natural light effect. Sunlight passes through the submerged entrance, reaches the pale sandy bottom and is reflected into the interior. The relationship between water, rock and incoming light is what makes a boat visit different from simply looking at the outside of the island. It is not a display produced by blue lamps or bioluminescence.
The Komiža tourism organisation recommends the period around 10:00 to 14:00 for the light, depending on the season. That recommendation helps orient the day without setting opening hours or promising a particular intensity. Reaching Mezuporat also involves boarding arrangements and possible waiting. Read the weather and timing guide before choosing the date around a photograph.
Ransonnet and the cave's international reputation
The municipal visitor information associates the cave's international recognition with the Viennese painter Baron Eugen Ransonnet in 1884. The useful historical distinction is between making a place internationally known and claiming its first discovery. Ransonnet belongs to the story of its wider reputation; that wording leaves room for the island's own earlier knowledge of its coast.
Since 1951 the Blue Cave has been protected as a geomorphological nature monument. Plan the visit as an encounter with a protected natural feature. This status concerns the cave and should not be turned into a national park identity or used to add a separate national park charge to your budget.
The visitor centre and local cave boats
The local admission list includes access to the visitor centre's multimedia exhibition, alongside the transfer and cave visit. These services give context to the short boat experience. They remain separate from the longer journey to Biševo, whether that journey begins on Vis or on the mainland. See admission and local boat arrangements when comparing the services in your excursion.
The municipal visitor information describes visits accompanied by the concession operator, with departure from Mezuporat. This is a boat visit rather than an independent walk into the cave. The entrance is low, and passengers may need to duck as directed by the crew. Consider the actual boarding and boat conditions when deciding whether the outing suits your party.
Line 612: Mezuporat, Salbunara and Porat
Scheduled line 612 links Komiža with Biševo. Mezuporat, Salbunara and Porat appear in its timetable, but the calls depend on the particular sailing column. A connection to the island is therefore not enough information on its own: select the bay you need and check that the return sailing works for your intended visit.
For 1 November to 31 December 2026, the timetable lists Tuesday, Friday and Sunday, excluding 25 December. Some sailings omit intermediate stops. Treat this as a dated winter transport pattern, not a daily shuttle or evidence that the cave operates whenever a scheduled boat runs. Local excursions from Komiža are another way to organise the crossing and should be compared as excursions.
Island rules and a weather-aware visit
The municipal code of conduct, published without a date, asks visitors not to disturb, catch or pursue wildlife, to leave no rubbish, avoid fires and follow marked paths. It also specifies keeping dogs on a lead and prohibits camping on Biševo. Use these as practical conduct rules rather than presenting them as a newly introduced regulation for the current year.
For the Blue Cave itself, the same municipal guidance prohibits bathing, swimming and diving. Snorkelling equipment on an excursion belongs to suitable outside stops. Commercial filming and photography require permission through More i krš under the municipal guidance; an ordinary boat booking is not that permission.
South winds, high water or rough seas can affect access and the wider route. Keep the return journey workable and follow the crew's instructions. An excursion that includes the cave in its route should not be read as a promise of unrestricted time elsewhere on the island. Match the programme to the kind of visit you want before choosing between a tour and scheduled transport.
Questions about Biševo
Are Balun and Mezuporat the same place?
Balun is the bay containing the cave. Mezuporat is the nearby departure bay used for the local cave visit boats.
What creates the blue colour?
Sunlight enters through a submerged opening and reflects from the pale sandy bottom into the cave. It is a natural optical effect.
Did Ransonnet discover an unknown cave?
The historical account credits him with making it internationally known in 1884. That is a description of its wider recognition, rather than a claim about the first person to know the cave.
Which line 612 sailings call at Mezuporat?
Calls differ between timetable columns. Choose the sailing for the bay you need, then plan the return separately from the local cave visit.