POTHA - the sunken city of Telendos Island.
Until 554 AC, Telendos and Kalymnos were one island. Then an earthquake sank a piece of land and separated Telendos from Kalymnos. Part of Potha city sank too.
We don't know much about the sunken city of Potha. But ruins on Telendos Island proclaim that Potha was a large city. Ruins of huge churches, of Roman baths and of an ancient theater.
A few submerged ruins are visible on the coast of Telendos Island. While extensive posidonia medows cover the rest of the sunken city.
Scuba diving is not allowed in the area shown in the map. Although snorkeling and freediving is allowed. We do scuba dive the frontiers though.