Modra špilja, Biševo (kod Visa) · 크로아티아 달마티아 비스(비셰보섬)
Location
Overview
The Blue Cave (Modra špilja) is a sea cave in Balun cove on the islet of Biševo, near Vis in Croatia's Dalmatian archipelago. Sunlight enters through a submerged opening and reflects off the pale seabed, flooding the whole chamber with a fluorescent blue glow — the Adriatic's most famous version of the phenomenon. The water is shallow (about 1–5 m) and clear enough for 15–25 m visibility, a vivid turquoise that reaches 20–24 °C in summer. Note, though, that swimming and snorkeling inside the cave have been banned since 2019: you visit it only by small boat for a brief 5–10 minute look. Actual snorkeling happens at nearby stops on the same trip — Porat beach on Biševo, the Green Cave on Ravnik islet, and the Blue Lagoon off Budikovac. As of 2026 the cave is still reached only by ticketed small-boat transfer, with long queues in peak season.
The optical spectacle: sunlight through the submerged opening reflects off the seabed and lights the cave in fluorescent blue — usually strongest around 11:00–12:00 in summer
A low entrance roughly 1.5 m high — you transfer from the tour boat to a small dinghy and duck down to enter
Shallow, transparent turquoise water 1–5 m deep with 15–25 m visibility
Snorkel stops paired on the same tour: Porat on Biševo (a sheltered sandy, pine-fringed bay), the Green Cave on Ravnik (swimming and snorkeling allowed), the Blue Lagoon off Budikovac, and Stiniva cove
Combine it as a full-day boat trip from Komiža/Vis, or a speedboat day tour from Split, Hvar, or Trogir
Good to know
RulesSwimming and snorkeling inside the Blue Cave (Modra špilja) are completely forbidden. You only view it from a small boat for a few minutes; 'More i krš' nature-protection wardens enforce the rules and issue fines. Save your mask and fins for the nearby stops.
SeasonWhen there is swell or waves, the low entrance is impassable and the cave closes for the day. Calm mornings in June–August give the best chance of entry, and the blue glow is strongest around 11:00–12:00. Always check the day's sea state and whether trips are running before you book or set off.
SafetyThe real snorkeling happens in open water at Porat, the Green Cave, and the Blue Lagoon, where tour boats and dinghies come and go constantly. Stay close to shore, tow a bright float or buoy, never snorkel alone, and watch for currents that can push you offshore. Beginners should not underestimate this.
SafetyRocky entry points are full of sea urchins, so wear water shoes, and the summer Adriatic sees occasional jellyfish (Pelagia noctiluca). Beginners should acclimatize in the shallows first to avoid mask fogging and surface panic, and watch for cold and fatigue during long spells in the water.
MannersAt the Green Cave and Porat, don't stand on or touch the rocks, seagrass, or marine life, and never apply sunscreen inside a sea cave (it's against the rules). Take nothing — shells, stones, or anything else — away with you.
CautionThe cave entrance fee (roughly €15–24, confirm the latest) is often not included in the tour price and is paid separately on-site. Any listing claiming you can 'swim inside the cave' is false, and terms differ by operator on days when waves prevent entry — check exactly what's included and the cancellation policy before booking.
Practical info
The cave is reachable only by boat: take a full-day boat trip from Komiža/Vis (about 5–6 nautical miles from Komiža), or a speedboat day tour from Split, Hvar, or Trogir (roughly 1.5–2.5 hours each way). The season runs roughly April–October, best in June–August, with the blue glow strongest in late-morning light around 11:00–12:00. Since you can't snorkel inside the cave, choose a trip that also stops at Porat, the Green Cave, or the Blue Lagoon. Confirm the entrance fee, departure times, what the price includes, and whether the cave is open on the day, using the latest information right before you book.
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