Blue Grotto (Plava Špilja)

A sea cave cut into the limestone cliffs on the western Lustica coast, the Blue Grotto, known locally as Plava Špilja, faces the open Adriatic. The cave entrance is wide enough to admit small boats, and at midday on clear days the sunlight passes through the water and reflects off the sandy floor, filling the cave interior with a deep blue glow that gives it its name. There is no beach at the Blue Grotto. This is a swim and photography stop rather than a sunbathing destination.

Boats typically anchor just outside the cave entrance and swimmers enter the water directly. Inside the cave the water stays consistently clear and cool, with depths of around five metres and underwater visibility above 20 metres in calm conditions. The cave is reachable only by boat. Direct access is impossible from land because the cliff walls above the cave are sheer and there is no descent path.

Visit timing matters significantly. The blue glow effect depends on both sea conditions and sun angle: flat water, clear skies and a midday sun between 11:00 and 14:00 produce the strongest effect. Overcast days and afternoon arrivals show only the cave structure without the colour display. Winter swells close the cave entrance to small boats entirely.

Standard Lustica boat tours from Herceg Novi include the Blue Grotto alongside stops at Žanjic, Arza and Mamula island. A private water taxi direct to the cave runs €60 to €100 return depending on the boat and season.