Thonis-Heracleion is a submerged site in Egypt, Africa. European Institute for Underwater Archaeology dates it to c. 7th to 2nd century BCE. Its listed material is Granite. European Institute for Underwater Archaeology also records: “Port and religious center.”
A great Egyptian port rediscovered in 2000 beneath Abu Qir Bay.
What makes it extraordinary
Soil Liquefaction and Catastrophic Submersion
The city's eventual disappearance was caused by a combination of rising sea levels, earthquakes, and tsunamis. A critical event occurred around 101 BC when a severe flood or earthquake triggered soil liquefaction on the central island. The region's hard clay rapidly transformed into a liquid state, causing the heavy stone buildings to collapse into the water. While a small population remained through the Roman and early Arab periods, the site was completely submerged by the end of the eighth century AD.
Systematic Underwater Excavation and Conservation
Excavations at Thonis-Heracleion utilize a rigorous grid reference system to document the exact positioning of every artifact. Divers use water dredges to uncover items, which are then tagged and photographed in situ. While the general policy is to leave artifacts in place, significant finds are raised using baskets or shipboard cranes. Once recovered, these items undergo a critical desalination process to prevent damage from exposure to dry air. As of recent reports, only approximately 5% of the city's total area has been excavated.
Advanced Non-Intrusive Mapping Technologies
To locate and map the submerged ruins, Franck Goddio's team employed a suite of cutting-edge, non-intrusive technologies. This included nuclear magnetic resonance magnetometers, multi-beam bathymetry, sidescan sonar, and sub-bottom profilers, integrated with satellite positioning systems. These tools allowed researchers to create precise 3D high-resolution maps of the seabed and sub-seabed sediments. This technological approach was essential for navigating the complex underwater environment of Abu Qir Bay, where the city had been buried under sand and debris for 1,200 years.
World's Largest Ancient Ship Deposit
The waters surrounding Thonis-Heracleion contain approximately seventy sunken ships, representing the largest deposit of ancient vessels ever discovered. This collection provides unprecedented data for nautical archaeologists regarding ancient shipbuilding styles and materials. Notable finds include a 25-meter Ptolemaic galley that utilized classic Greek mortise and tenon joints combined with Egyptian flat-bottomed construction suitable for the Nile. Many of these ships were preserved because they were pinned to the seafloor by heavy stone blocks falling from collapsing buildings during the city's destruction.
Epigraphic Proof of City Identity
For centuries, historians believed Thonis and Heracleion were two distinct cities. This was corrected in 2000 with the discovery of a black granodiorite stele at the site's temple. The artifact, a decree by King Nectanebo I, explicitly ordered that the stele be placed in the city of 'Thonis,' despite being found in the location known to Greeks as Heracleion. This find, along with its twin 'Stele of Naukratis,' solidified that the two names referred to the same urban center, known by its Egyptian and Greek names respectively.
Discovery of Monumental Statuary and Artifacts
Excavations have yielded massive, intact statues, including a depiction of the god Hapi holding a tray of bread and a statue of a Ptolemaic queen (either Cleopatra II or III) dressed as the goddess Isis. Other significant finds include incomplete statues of Serapis and Arsinoe II, ritual animal sarcophagi, gold jewelry, and coins from the reign of Ptolemy II. These artifacts were often found preserved in underground rooms or buried beneath the debris of collapsed buildings, protecting them from looters for over a millennium.
Canal-Based Urban Planning and Connectivity
Thonis-Heracleion was originally constructed on a series of adjoining islands within the Nile Delta, featuring a central temple as its focal point. The city's layout was defined by an intricate network of canals that intersected the urban area, facilitating movement between various harbors and anchorages. To maintain connectivity across these waterways, the city utilized a sophisticated system of ferries, bridges, and pontoons that linked its diverse structures, including wharves, temples, and multi-story tower-houses, creating a highly integrated maritime urban environment.
Primary International Trade Hub and Tax Collection
During the Late Period, Thonis-Heracleion served as Egypt's primary emporion for international trade and a critical center for tax collection. The city functioned as a gateway for goods entering the country, which were then transferred inland via its sister city, Naucratis, or transported through the Western Lake to Canopus. Historical records, specifically the Decree of Nectanebo I, confirm that ten percent of all import taxes collected at Thonis were mandated to be donated to the sanctuary of Neith of Sais.
Religious Centers and the Mysteries of Osiris
The city was a major religious destination, housing a large temple dedicated to Amun-Gereb and a temple for Khonsu, whom the Greeks identified with Herakles. It was also famous for sanctuaries dedicated to Osiris that were renowned for miraculous healing, drawing pilgrims from across the region. A significant annual event was the 'Mysteries of Osiris' in the month of Khoiak, where the deity was transported in a ceremonial boat procession from the temple of Amun in Thonis to his specific shrine in nearby Canopus.
Evidence of Greek and Egyptian Coexistence
Archaeological evidence confirms a significant Greek presence in Thonis-Heracleion as early as the Twenty-sixth Dynasty. Discoveries include a Greek sanctuary dedicated to Aphrodite, a tholos temple, and numerous Greek ceramics, some imported from Attica. The presence of Greek weapons and specific burial tumuli containing Greek offerings suggests that Greek mercenaries and merchants were well-integrated into the city's defense and economy. This multiculturalism is further evidenced by hybrid shipbuilding techniques that blended Greek structural joints with Egyptian hull designs for river navigation.