Goods were transferred inland via Naucratis, or they were transported via the Western Lake and through a water channel to the nearby town of Canopus for onward distribution.

[8] Sanctuaries in Heracleion dedicated to Osiris and other deities were famous for miraculous healing and attracted pilgrims from a wide area.

[17] Earthquakes can also cause liquifaction, and earth tremors and tidal waves were reported by ancient historians during the time of Thonis-Heracleion's submersion.

A few residents stayed on during the Roman era and the beginning of Arab rule, but by the end of the eighth century AD, what was left of Thonis had sunk beneath the sea.

[8] These references to Thonis-Heracleion are often within the context of a story about legendary Greek figures, such as Heracles and Paris, and put the location of the city to be on the coast and adjacent to the Nile.

[21] Diodorus made mention of Thonis in relation to a story of Heracles, claiming that at one point the Nile river had become greatly inundated and flooded the area in which Prometheus was the governor.

[22] Due to the speed that its water flowed, the Nile at that time was called the Aëtus, or eagle, until Heracles stopped the flooding and corrected the river's course back to its original position.

[23] Diodorus claimed that the myth of Heracles slaying the eagle which ate the liver of Prometheus had its origins in this event, and that the city of Thonis stood where the Nile now emptied into the Mediterranean.

[10] Herodotus said that Paris and Helen of Troy, fleeing from Menelaus, landed in a region of the Nile delta known as the Canopic mouth.

The second century BC Greek poet Nicander wrote that Menelaus's helmsman, Canopus, was bitten by a viper on the sands of Thonis.

[9] Until very recently the site had been known only from a few literary and epigraphic sources, one of which interestingly mentions the site as an emporion, just like Naukratis.|British Museum, 2013[6]}} Heracleion is also mentioned in the twin steles of the Decree of Nectanebo I (the first of which is known as the 'Stele of Naukratis'), which specify that one tenth of the taxes on imports passing through the town of Thonis (Heracleion) were to be given to the ancient sanctuary of Neith of Sais.

[6] The city is also mentioned in the Decree of Canopus honoring Pharaoh Ptolemy III, which describes donations, sacrifices and a procession on water.

[7] The ruins submerged in the sea were located and excavated by the French underwater archaeologist Franck Goddio and his team of the IEASM[27] in collaboration with the Ministry for Antiquities of Egypt after a five-year search.

The team conducted dives at the site in a tightly coordinated schedule for about a month period in order to maximize their time there.

[18] Once on the ship, the artifacts were cleaned and then went through a desalination process in order to protect them from the dry air after a long submersion underwater.

[32] The quick destruction of the buildings and slow submersion of Thonis-Heracleion allows archaeologists to now study the underwater city with its surplus of archaeological evidence.

[18] Many gold coins, statues of deities, jewelry, ritual animal sarcophagi, and ceramic pieces were uncovered at the site; these artifacts give archaeologists a wide range of items to study.

In July 2019, a tholos, small Greek temple, ancient granite columns, treasure-carrying ships, and bronze coins from the reign of Ptolemy II, dating back to the third and fourth centuries BC, were found at Thonis-Heracleion by IEASM, a team of Egyptian and European archeologists led by Goddio.

This ancient war ship in the sunken city was trapped under heavy materials, such as stone, that fell from the crumbling buildings during the catastrophes that caused Thonis-Heracleion's destruction.

The ship was harbored near the Temple of Amun, and it was held in place on the ocean floor by the heavy building materials until its discovery.

[43] Also, a tumulus was discovered, covered with numerous offerings including wicker baskets containing fruits of the doum palm tree and grape seeds dating to the early 4th century BC, alongside a number of Greek ceramic some with black and red figures likely imported from Attica;[44] a wooden sofa used for banquets was also found, alongside a gold amulet of high quality.