Amazing Underwater Lakes Beneath Santorini

Beneath the towering cliffs of the caldera between Oia and Imerovigli, there is an unexpected phenomenon. There are carbon pools that shimmer with colors of opal within cavities of the seabed.

Beneath the towering cliffs of the caldera between Oia and Imerovigli, there is an unexpected phenomenon. There are carbon pools that shimmer with colors of opal within cavities of the seabed. The "Kallisti Limnes" as these formations are named, are the first underwater lakes of their kind, says the international research team.

The underwater lakes consist of dense water that sinks to the bottom of the sea instead of mixing with seawater. To date, however, all the already known submarine lakes are formed from water which is enriched with large quantities of salt; so it becomes denser than the water in the surrounding environment.
The 'Kallisti Limnes' differ. "We've seen pools within the ocean before, but they've always been brine pools where dissolved salt released from geologic formations below the seafloor creates the extra density and separates the brine pool from the surrounding seawater," said Rich Camilli, a researcher of the famous Oceanographic Institute of Woods Hole in Massachusetts. "In this case, the pools' increased density isn't driven by salt – we believe it may be the CO2 itself that makes the water denser and causes it to pool." he adds.

The Institute collaborated on the research with the University of Athens, the Greek Centre for Marine Research and research institutions from Spain and France.
The underwater research began after the alarming magma buildup that began in 2011 under the big volcano in Santorini. The lakes were discovered at a depth of 250 meters from robotic submarine which was studying a large crack in the caldera of the volcano (the crater collapsed after a giant explosion that wiped out the Minoan civilization around 1600 BC. The island is what remained above the sea level).

The lakes were also studied by a robotic vessel and a manned submarine. The field tests showed that the translucent formulations contain large amounts of dissolved carbon dioxide and having a temperature of about 5 degrees higher than the surrounding water. Furthermore, the lakes are quite acidic and hostile to most microorganisms. However, they may host microbes that produce silica; This would explain the strange, milky and iridescent appearance of underwater layers.
The carbon dioxide in the pools must come from the bottom. The volcanic complex of Santorini is the most active part of the Greek volcanic arc, where the African tectonic plate slides under the Eurasian plate. The CO2 may come from magma that releases the gas. Another explanation is that it comes from limestone dipped and subjected to extreme pressures and temperatures.

It is claimed that the underwater lakes are probably transitory formations. Their discovery was made possible thanks to the progress of submarine research technologies. The project has also received funding from NASA's Astrobiology, studying unusual environments on Earth that could give an insight into life on other planets.