For centuries, one of ancient Egypt’s most important port cities existed only as a name in old texts, a place Greek writers called Heracleion and Egyptians called Thonis. Then, in 2000, divers working in Aboukir Bay off the coast near Alexandria began raising colossal statues, temple blocks and gold from the seabed. The lost city was real, and it had been lying under the Mediterranean the whole time.
More than two decades later, teams are still bringing it up piece by piece. Each diving season adds new treasures and new questions, and the archaeologists who work the site estimate that the vast majority of it has yet to be touched. The sunken city keeps giving because so little of it has actually been explored.
Thonis-Heracleion, Egypt’s vanished gateway
Before Alexandria was founded in 331 BCE, Thonis-Heracleion was Egypt’s main port on the Mediterranean, the customs point where ships from across the Greek world entered the mouth of the Nile. It sat on the edge of the delta, threaded with canals and dominated by a great temple to the god Amun-Gereb. For a long stretch of the first millennium BCE it was a bustling hub of trade, religion and taxation, a doorway between Egypt and the sea.
Two names confused historians for generations. Greek sources spoke of Heracleion, Egyptian records of Thonis, and it took the underwater discoveries to prove they were the same settlement. The city has since given up steles inscribed in both hieroglyphs and Greek, the kind of bilingual evidence that pins a place firmly into the historical record.
How a city ended up on the sea floor
The site now lies about four miles offshore under roughly thirty feet of water and sediment. Its collapse was not a single dramatic night but a slow drowning. The delta soils beneath the city were soft and waterlogged, and a combination of rising seas, subsidence and possibly earthquakes caused the ground to liquefy and give way. Heavy stone buildings sank into the mud, and by around the eighth century CE the city had effectively slipped beneath the waves.
That gradual burial is why so much survived. Statues fell and were cushioned in silt, gold jewelry settled into the seabed, and ceramic vessels and ritual objects were sealed away from looters. The mud that swallowed Thonis-Heracleion also protected it.
The divers still mapping the ruins
The rediscovery is largely the work of underwater archaeologist Franck Goddio and the European Institute for Underwater Archaeology, whose surveys located the site and have documented it ever since. Their excavation of Thonis-Heracleion has raised more than sixty ancient shipwrecks, hundreds of anchors, colossal statues of gods and pharaohs, and coins spanning centuries of trade. Recent seasons have uncovered the remains of a temple to Amun that collapsed in the mid-second century BCE, along with a Greek sanctuary to Aphrodite, gold objects and a lapis lazuli amulet.
Modern methods make the slow work possible. Geophysical surveys map buried structures before divers ever descend, and photogrammetry stitches thousands of underwater photographs into precise three-dimensional models of each find in place. The result is not just recovery but reconstruction, a digital city rebuilt from a drowned one.
The finds also rewrite the economic history of the region. Customs steles recovered from the site record the taxes levied on goods passing through, and the sheer number of anchors and shipwrecks confirms just how busy the harbor once was. Colossal statues, including a figure of the Nile-flood god Hapi and images of Ptolemaic rulers standing more than sixteen feet tall, once presided over the temples that are now scattered across the seabed. Together they portray a port that was simultaneously a religious center, a trading gateway and an instrument of royal revenue, its wealth flowing through canals lined with sanctuaries.
Why the excavation is far from finished
By the researchers’ own estimates, only a small fraction of Thonis-Heracleion has been surveyed, which is what turns the site into a decades-long project rather than a single discovery. The work has been supported over the years by partners including the Hilti Foundation, whose backing has helped fund the diving seasons that keep the finds coming.
What has already emerged has reshaped understanding of the late pharaonic and early Greek periods in Egypt, offering a rare snapshot of a working port frozen at the moment it slid underwater. The temples, ships and inscriptions together sketch a cosmopolitan crossroads where Egyptian and Greek worlds met.
Because the seabed still hides the greater part of the city, each season carries the possibility of another temple, another wreck or another cache of gold. The story of Thonis-Heracleion is one of the few in archaeology where the phrase “still being discovered” is literally true, year after year, as divers keep pulling a lost city up from the dark.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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