From Franck Goddio’s website:
Thonis-Heracleion (the Egyptian and Greek names of the city) is a city lost between legend and reality. Before the foundation of Alexandria in 331 BC, the city knew glorious times as the obligatory port of entry to Egypt for all ships coming from the Greek world. It had also a religious importance because of the temple of Amun, which played an important role in rites associated with dynasty continuity. The city was founded probably around the 8th century BC, underwent diverse natural catastrophes, and finally sunk entirely into the depths of the Mediterranean in the 8th century AD.
Prior to its discovery in 2000 by the IEASM, no trace of Thonis-Heracleion had been found. Its name was almost razed from the memory of mankind, only preserved in ancient classic texts and rare inscriptions found on land by archaeologists. The Greek historian Herodotus (5th century BC) tells us of a great temple that was built where the famous hero Herakles first set foot on to Egypt. He also reports of Helen’s visit to Heracleion with her lover Paris before the Trojan War. More than four centuries after Herodotus’ visit to Egypt, the geographer Strabo observed that the city of Heracleion, which possessed the temple of Herakles, is located straight to the east of Canopus at the mouth of the Canopic branch of the River Nile.
The full story of the discovery of Heracleion can be found on Franck Goddio’s website along with some beautiful photos of the underwater ruins and artefacts that were recovered from the site. It doesn’t take a huge stretch of the imagination to picture a certain fictional archaeologist exploring this mysterious and breathtaking sunken city, searching for lost ancient treasures and fending off the occasional shark. Something for a future Tomb Raider game perhaps..? ;)