Located on the island of Biševo, off Vis' southwestern tip, this coastal cave is one of the region's most famous natural sights. It's at its best between 11am and noon, when the sun’s rays pass through an underwater opening, bathing the interior in an unearthly blue light. Beneath the translucent water, rocks glimmer in silver and pink to a depth of 16m. To get here, the easiest, quickest and best option is to take a tour from Komiža.
A huge increase in visitor numbers over recent years has made the experience much less pleasant, and it's no longer possible for boats to linger within the cave or for people to jump out for a swim. Even with the hefty admission charge, the line of boats waiting to get in can be discouragingly long – and many tours don't even attempt to visit when the blue glow is at its peak. Crowding isn't such a problem in winter, but it's difficult to find a boat and the water can be too choppy to enter the cave due to the prevailing jugo (southern wind).
In summer tours head to the cave from all over Vis, the surrounding islands and as far away as Split. From Komiža, the trips take between an hour and 90 minutes, depending on the waiting time to enter the cave. Expect to pay around 100KN (or 140KN including a lunch stop) for a trip on a rigid-inflatable speedboat, in addition to the admission charge.