Thonis-Heracleion — Egypt's Lost Port

Thonis-Heracleion sat on soft, waterlogged sediment at the mouth of the Canopic branch of the Nile — ground that had always been unstable, and that grew more so as the weight of temples, harbour works and centuries of accumulated buildings pressed down on it. Archaeologists now believe the city's end came through a combination of gradual land subsidence, soil liquefaction possibly triggered by earthquake activity, and a rising Mediterranean sea level, rather than any single catastrophic night.

The Greek historian Herodotus, writing in the 5th century BCE, describes Thonis as the mandatory entry port for the Nile, where a great temple to Herakles stood — the same temple in which, according to a later legend, Helen and Paris supposedly stopped en route to Troy, delaying their journey long enough for the priests to record it. Diodorus Siculus and inscribed temple decrees confirm the city's importance for centuries after Herodotus. By the 2nd century BCE, the rise of nearby Alexandria had already begun to eclipse it; by the 8th century CE, the sea had finished the job.

French underwater archaeologist Franck Goddio began surveying Abu Qir Bay in 1996 with the European Institute for Underwater Archaeology (IEASM), using magnetometers to detect anomalies beneath metres of sand and sediment on a seafloor with essentially zero visibility. In 2000, after years of methodical survey work, his team's divers found the outline of massive stone structures exactly where the magnetic readings predicted — the beginning of what would become one of the largest underwater excavations ever undertaken.

What emerged over the following two decades was staggering in scale: the remains of the great Temple of Amun-Gereb, over 700 ancient anchors, more than 60 shipwrecks preserved in the anaerobic mud, hundreds of small votive objects, gold jewellery, and a series of colossal statues — including a red granite figure of the god Hapy over five metres tall, and a pair of similarly massive statues of a Ptolemaic king and queen that once flanked the temple entrance.

Among the most significant single finds was a nearly intact black granodiorite stele, 1.9 metres tall, commissioned around 380–362 BCE by Pharaoh Nectanebo I. Its inscription, nearly identical to a previously known stele from Naukratis, names the site explicitly as Thonis — and its findspot was unmistakably within the ruins the Greeks had called Heracleion. The stele resolved a genuine scholarly uncertainty that had persisted since antiquity: Thonis and Heracleion were not two neighbouring cities, nor one city known by two names to two different peoples writing about the same place from different angles — they were, definitively, one and the same.