Dragon's Eye Lake

Zmajevo Oko is a roughly circular lake about 120 metres across on the Rogoznica peninsula, formed when the roof of a sea cave collapsed, connected to the sea underground so its level moves with the tide. What makes it scientifically interesting is that the water is layered and does not mix: the upper layer is oxygenated, the lower is saline, still and full of hydrogen sulphide, and when strong conditions overturn the column the sulphide reaches the surface and kills the fish - documented events have turned the whole lake milky and left it dead for a period before it recovers. It is a protected geomorphological monument.

The landscape

• A collapsed sea cave - about 120 metres across, tidal through the rock.
• Water that does not mix - oxygenated above, sulphide-rich below.
• Overturn events that kill the fish - documented and recurring.
• A protected monument - for the geomorphology and the chemistry.

When to go

May to September. Two hours.

Practical notes

Swimming is discouraged and at times unsafe because of the chemistry. The banks are steep rock with limited access to the water. After an overturn the lake smells strongly and looks dead. Facilities are none.

Nearby

Rogoznica marina is next door; Primosten is north-west along the coast.

Key facts