The cave is located under the car park area which can be found adjacent to Vouliagmeni lake in Athens. A great dive with interesting formations of solid rock, sand, and clay. Peculiar to find half way into the cave a small wooden boat which sank some time in the past. 

The waters of the lake come from over 100 meters depth and have a temperature of 22 ° C to 29 ° C, indicating that at some depth it communicates with the Aegean volcanic arc. The lake is also powered by a freshwater source at a depth of 17 meters. The lake meets with an underground cave that communicates with the sea through various arcades. The lake is located on the southern tip of Ymittos, near the sea. It lies in an ellipsoidal cavity 260 meters long and 145 meters wide. The lake is half a meter above sea level and has been part of the Natura protected areas since 2000.

The lake was created when part of the roof of a large underground cave collapsed some 2,000 years ago due to erosion and tectonic movements, and therefore there are no references from antiquity, not even Pafsanias. The cave is located within the limestone rocks of the surrounding area. The explored length of the cave is 3,123 meters. There are 14 tunnels in the cave, and a large underwater stalagmite has been found. The bottom of the lake consists of a muddy substrate rich in sulfur compounds. The lake waters have an increased content of minerals and trace elements, such as potassium, sodium, lithium, ammonium, calcium, iron, chlorine and iodine. The water is recommended for rheumatic diseases, sports injuries, nervous system disorders, skin diseases and gynecological diseases.