At a glance
Beneath the calm, murky waters of Abu Qir Bay — just 30 kilometres east of modern Alexandria — lie the submerged ruins of two ancient Egyptian cities that rank among the greatest archaeological discoveries of our time. Thonis-Heracleion, once Egypt's most important Mediterranean port, and Canopus, a celebrated sanctuary city famed across the ancient world, were both swallowed by the sea some time between the 2nd and 8th centuries AD, their existence surviving only in the writings of ancient historians who were eventually dismissed as fabulists.
Today, thanks to the pioneering work of French underwater archaeologist Franck Goddio and his team at the European Institute for Underwater Archaeology (IEASM), these cities are gradually giving up their secrets. Thousands of extraordinary artefacts — colossal statues, gold jewellery, intact pottery, sacred inscriptions, and an entire fleet of sunken ships — have been recovered from the seabed, rewriting our understanding of Egypt's late Pharaonic and Ptolemaic eras.
Key fact: Thonis-Heracleion is the same city known by two names — Thonis to the Egyptians and Heracleion to the Greeks. A decree stele found on the seabed confirmed this long-debated identity in one remarkable moment of discovery.
Table of contents
1) The Cities Lost to Legend
For centuries, scholars debated whether the cities described by ancient writers truly existed, or whether they were simply literary embellishments of a grander past. Herodotus, writing in the 5th century BC, described Heracleion as a great port city at the mouth of the Nile, and referenced a famous temple of Herakles there. The Greek geographer Strabo wrote of Canopus as a place of immense religious significance and vibrant festivity, where Alexandrians would travel by canal barge to participate in joyous celebrations. Yet by the medieval period, both cities had vanished entirely from the landscape and from living memory.
The ancient texts were all that remained — fragments of description scattered across dozens of classical sources — and many historians treated them with scepticism. The idea that entire cities could simply disappear beneath the sea seemed extraordinary. It was not until the systematic application of modern underwater survey technology, combined with decades of patient fieldwork, that the truth finally emerged from the depths.
Ancient Accounts of the Cities
Among those who described these places were some of antiquity's most respected writers. Herodotus visited Egypt around 450 BC and described Heracleion's temple personally. Diodorus Siculus, Strabo, and later Ammianus Marcellinus all referenced Canopus as a thriving religious and leisure destination beloved of the Alexandrian population. The sheer number and consistency of these independent accounts is what led Goddio to take the search seriously.
2) The Discoverer: Franck Goddio
Franck Goddio is a French underwater archaeologist who, after a career as a financial expert at the United Nations, turned his full attention to maritime archaeology in the 1980s. He founded the European Institute for Underwater Archaeology (IEASM) in Paris and developed new methodologies for deep-water surveying — combining nuclear magnetic resonance (NMR) equipment, sub-bottom profilers, and multi-beam sonar to detect buried structures beneath metres of sediment on the seabed.
In 1996, in partnership with the Egyptian Supreme Council of Antiquities, Goddio began a systematic survey of Abu Qir Bay. The results, which emerged over the following years, astonished the world. In 1999, his team located the remains of Canopus. In 2000, they confirmed the position of Thonis-Heracleion. Excavations at both sites have continued every year since, and the volume of finds has grown steadily into one of the most remarkable archaeological inventories ever assembled from a single underwater area.
The Hilti Foundation Partnership
Since 1996, Goddio's expeditions have been made possible through a long-term partnership with the Hilti Foundation. This private funding model has allowed excavations to continue consistently over nearly three decades, resulting in a uniquely comprehensive picture of the submerged landscape. Many of the recovered artefacts have been exhibited internationally in partnership with the British Museum and other major institutions.
3) Thonis-Heracleion: Egypt's Grand Port
Thonis-Heracleion occupied a strategic position at the Canopic mouth of the Nile — the primary entry point into Egypt from the Mediterranean world during the Late Period and Ptolemaic era (circa 7th century BC to the 3rd century AD). Every ship entering Egypt from Greek, Phoenician, or other Mediterranean ports was legally obliged to pass through Thonis-Heracleion first, where customs duties were levied and cargo was inspected. This made it an extraordinarily wealthy city, and its excavated remains reflect that prosperity in remarkable fashion.
Key Finds at Thonis-Heracleion
| Artefact / Feature | Details |
|---|---|
| Colossal statues | 5-metre pink granite figures of a pharaoh, a queen, and the god Hapy |
| Decree stele | Confirmed the dual name Thonis / Heracleion on a single inscription |
| Sunken ships | Over 70 ancient vessels found in the harbour basin |
| Bronze objects | More than 700 ancient anchors and hundreds of bronze coins |
The Temple of Amun-Gereb
At the heart of Thonis-Heracleion stood a grand temple dedicated to the god Amun-Gereb, considered the supreme deity of the city. The temple's remains — including its enormous pink granite naos (shrine), ritual vessels, and priestly equipment — have been recovered from the seabed and demonstrate that this was one of the most lavishly equipped sanctuaries in the Delta region. The temple played a vital role in the Egyptian religious calendar, hosting the annual mysteries of Osiris during the month of Khoiak.
The Harbour Network
Extensive survey work has revealed that Thonis-Heracleion was built on a complex network of islands, channels, and basins — a waterborne city in the style of a delta settlement. More than 70 ancient ships have been identified within its harbour basins, making it one of the richest concentrations of ancient maritime material in the world. The ships range from small wooden barges to large merchant vessels, some still carrying their original cargo of pottery and bronze objects.
4) Canopus: City of Festivals and Faith
Lying approximately 2.5 kilometres east of Thonis-Heracleion on the seabed, the ruins of Canopus tell a different kind of story. Where Thonis-Heracleion was primarily a port of commerce and customs, Canopus was above all a city of religion, pilgrimage, and celebration. The city was famous in antiquity for two major temples — one dedicated to Osiris and one to the healing god Serapis — both of which drew pilgrims and worshippers from across the eastern Mediterranean. Classical authors described canal boat processions from Alexandria to Canopus as among the most joyous spectacles in the ancient world.
The excavations at Canopus have yielded remarkable devotional objects: exquisite bronze statuettes of gods and goddesses, ritual pottery used in the Osirian mystery rites, priestly equipment in gold and faience, and an extraordinary collection of Osiris-Canopus jars — ceramic vessels in the form of the god's mummified body — which are unique to this region. The site also preserves evidence of the Ptolemaic royal cult, with inscriptions and statuary confirming that the Ptolemaic kings actively maintained and expanded the city's temples.
The Synod of Canopus, 237 BC
Canopus was the site of a significant moment in Ptolemaic history: the Decree of Canopus, issued in 237 BC under Ptolemy III. The decree — found in multiple copies across Egypt — introduced calendar reforms and established new divine honours for the deceased princess Berenice II. Its trilingual format (hieroglyphic, Demotic, and Greek) places it in the same tradition as the Rosetta Stone, and it has been invaluable for scholars deciphering the interplay between Egyptian and Greek religious culture in the Ptolemaic period.
5) The Royal Quarters of Alexandria
In addition to the two sunken cities, Goddio's surveys in Alexandria's Eastern Harbour have revealed the submerged remains of what ancient sources describe as the royal palace quarter of Alexandria — the Brucheion. This was the magnificent royal district of the Ptolemaic kings and, later, of Cleopatra VII herself. Earthquakes and coastal subsidence during the 4th to 8th centuries AD caused this area of Alexandria's waterfront to slip beneath the sea, preserving an extraordinary archaeological record beneath just a few metres of water in the modern harbour.
The remains include foundations of royal pavilions, harbour installations, shipwrecks, and an enormous quantity of architectural fragments — column capitals, statue bases, granite blocks, and sphinxes — that give a powerful impression of the city's former grandeur. Among the most dramatic finds is what Goddio's team identifies as the location of Cleopatra's palace, making this shallow underwater zone one of the most historically charged archaeological sites in the world.
What Has Been Found in the Royal Quarter
- Sphinx statues: Multiple red granite sphinxes bearing royal cartouches, believed to have stood at the entrance to royal precincts
- Obelisks: Fallen obelisks of pink Aswan granite, some still inscribed with the names of Pharaohs Seti I and Ramesses II
- Shipwrecks: Several ancient vessel hulls, including a large warship, preserved in the harbour silt alongside their cargo
6) Why Did the Cities Sink?
The submersion of these cities was not the result of a single catastrophic event, but rather a gradual and multi-cause process that unfolded over centuries. Geological studies of the seabed sediments indicate that the Nile Delta region — including the area of Abu Qir Bay — sits on a foundation of unstable, water-saturated clays and silts deposited by the Nile over millennia. This substrate is inherently prone to liquefaction: when subjected to seismic shock, it loses its structural integrity and can cause buildings and entire districts to subside rapidly. Evidence of tsunami damage and earthquake-triggered collapse has been identified at multiple points within the Thonis-Heracleion site.
Compounding the seismic vulnerability was a long-term process of coastal subsidence: the land itself gradually sank relative to sea level, possibly accelerated by the extraction of groundwater and the reduced deposition of Nile sediment following major hydraulic works in antiquity. A combination of earthquake damage (major seismic events are recorded in the region around the 2nd century BC and again in the 4th and 8th centuries AD), tsunamis triggered by those earthquakes, rising sea levels, and gradual land subsidence ultimately overwhelmed both cities, leaving them submerged and forgotten. The remarkable state of preservation of many artefacts — including fragile bronze objects and intact ceramic vessels — is largely due to the rapid burial of the sites under protective layers of silt.
7) Visiting & Learning More
Where to See the Finds
- National Museum of Alexandria: Houses a permanent collection of key finds from Goddio's excavations, including the Decree of Canopus stele and bronze figurines
- Egyptian Museum, Cairo: Selected statuary and artefacts from the sunken cities appear in the collection alongside other Delta-region material
- Travelling exhibitions: The "Sunken Cities" exhibition (developed with the British Museum) has toured Paris, London, Melbourne, and other international venues
Practical Notes for Visitors to Alexandria
- The underwater sites themselves are not open to recreational divers — they are active, restricted archaeological excavation zones
- Abu Qir Bay is visible from the coastal road east of Alexandria; the general area of the submerged cities can be seen from the shore on calm days
- The National Museum of Alexandria (Kom el-Dikka area) is the primary on-site destination for seeing recovered artefacts in context
Suggested Alexandria Itinerary (1 Day)
- Morning (9:00 AM) — Visit the National Museum of Alexandria to see the sunken cities collection, including the stele, colossal statues, and Osiris-Canopus jars
- Afternoon (1:00 PM) — Drive east along the coast to Abu Qir Bay for views over the general location of the submerged cities, then visit the ancient site of Kom el-Dikka
- Evening (5:00 PM) — Explore the Eastern Harbour waterfront area of Alexandria, where the royal quarter lies just beneath the surface of the water
Last updated: April 2026. Museum opening hours and exhibition availability are subject to change; verify with local authorities or your tour operator before visiting.
8) Sources & Further Reading
The following are reputable starting points used to compile the information on this page.
- Goddio, Franck & Fabre, David. Egypt's Sunken Treasures. Prestel, 2008. — The definitive illustrated catalogue of the Abu Qir Bay excavations, co-published with the Hilti Foundation
- Goddio, Franck & Masson-Berghoff, Aurélia (eds.). Sunken Cities: Egypt's Lost Worlds. Thames & Hudson / British Museum Press, 2016. — Companion volume to the major international travelling exhibition
- Stanley, Jean-Daniel & Bernasconi, Maria Pia. Holocene depositional patterns and subsidence in Alexandria's Eastern Harbour, Egypt. Journal of Coastal Research, 2006. — Scientific analysis of the geological processes behind the cities' submersion
- Herodotus. The Histories (Book II). Penguin Classics edition, trans. Aubrey de Sélincourt. — The earliest literary source to describe the city of Heracleion and its temple of Herakles
Hero image: Colossal statues recovered from Thonis-Heracleion, photographed during excavation by Franck Goddio / Hilti Foundation. Sphinx image: Sphinx on the seabed, © Franck Goddio / Hilti Foundation. Images sourced via Wikimedia Commons under open licence.