A path of ancient rocks and red ochre ground separates the Dalmatian dock of Rogoznica, from a more enigmatic and peculiar place. At the base of the Gradina peninsula, nestled in the green blanket of the Mediterranean scrub, the Zmajevo Oko, or Dragon’s Eye lake, appears as an impenetrable ink blot.
By Marianna Morè
A stunning vision, the crater lake is surrounded by sheer and grey cliffs, whose height reaches 24 meters and which surround a basin of approximately 10.000 square meters. Its primitive appearance conveys the impression of a sudden collapse, as if the water had swallowed the vegetation and left a vaste, black hole. The lake was in fact formed in ancient times by the sinking of a subterranean cave vault, that subsided at the bottom of the pond.
However, it isn’t only this harsh vision that attracts scientists and tourists: the location is in fact a unique hydrogeomorphological environment on the Adriatic coast. The salted water of the lake comes from the nearby sea, its concavity being filled at the end of the Ice Age, when the sea level rose. The temperature varies in layers – the Dragon’s Eye lake is meromictic – and around 9 meters deep there is no more oxygen. On the contrary, the water is characterized by high levels of sulphuric hydrogen, a gas considered poisonous.
Even more surprising is what the locals call the boiling of the lake phenomenon. Named rollover in the engineering literature, the event is provoked by the mixing of the water column. The latter occurs when a heavier lower layer and a lighter upper layer of fluids overturn because of a sudden heat flux through the system, which can be due to earthquakes or seismic activities. In such cases, the oxigen concentration dramatically decreases and the water becomes supersaturated in CO2, sulphur and other gases that normally build up indisturbed at the bottom of meromictic lakes.
The change in the chemical composition modifies the color of the pond, that becomes white and milky as if boiling. But it also has a consequence on the marine species – such as oysters, crabs, shrimps and mussels – that populate it. Due to a lack of oxygen, they die abruptly, as it happened lately in 2011.
Because of its features, the Dragon’s Eye has been compared by scientists to the Black Sea, the Framvaren Fjord in Norway and Lake Pavin in France. But the greatest contribution this body of water has given, is to the imagination and the tradition of Rogoznica people. Many legends of a sometimes protective and sometimes merciless dragon are still commemorated in local festivities: the dark eye has maintained its misterious glance.
On a warm day I reach the edge of the lake for a plunge. The sun is setting and a lively group of young Dalmatians indulge in a long series of dives. I take a deep breath, streach my arms towards the water and lift my feet in the air with a leap. No boiling lake, no nasty dragons come in sight for the moment: just the dark fascination of a natural wonder.
Marianna Morè is a freeelancer writer and lives in Padova, Italy. She is a windsurfer, a scuba diver, an avid reader and a rather imaginative and creative woman. Her stories have been published by SEVENSEAS Media, the Italian edition of Christophorus, byGonomad.com and by a local newspaper.
Follow her blog at: https://shapeofclouds.wordpress.com/
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