Vouliagmeni Lake is a beautiful place to visit. It’s hot springs with 24ºC temperature all year round is an outdoor spa. At the bottom of the lake is the entrance to a labyrinthine submarine cave of 3,123 meters in length.
In this area is the largest underground tunnel in the world, with a length of 800 meters and width of 60 to 150 meters, while its average depth reaches 80 meters. The total length of the cave’s 14 underground tunnels reaches 4.3 kilometers.