What is "heracleion"

Heracleion , also known as Thonis , was an ancient Egyptian city near Alexandria whose ruins are located in Abu Qir Bay, currently 2.5 km off the coast, under of water. Its legendary beginnings go back to as early as the 12th century BC, and it is mentioned by ancient Greek historians. Its importance grew particularly during the waning days of the Pharaohs—the late period, when it was Egypt's main port for international trade and collection of taxes.

Heracleion was originally built on some adjoining islands in the Nile Delta, and was intersected by canals. It possessed a number of harbors and anchorages, was the sister city of Naucratis, and was superseded by Alexandria.