The underwater cities of Thonis-Heracleion and Canopus have long remained a mystery to archaeologists. Once thriving centers of trade and religion in ancient Egypt, relatively little has been known of them since they were consumed by the sea. All memory of them was in danger of disappearing as drastically as their physical remnants appeared to have been forgotten by time.

Inspired by accounts from the likes of Herodotus, however, French archaeologist Franck Goddio began surveying Abu Qir Bay, an area just west of the Nile Delta. His curiosity paid off in 2000, when he discovered two sets of ruins waiting patiently in the sand beneath the murky water. The treasures that awaited him have brought the captivating secrets of these submerged cities back to life.

Known as Thonis in ancient Egypt and as Heracleion by the Greeks, the underwater city of Thonis-Heracleion was one of ancient Egypt’s most important port cities. Founded around the 8th Century BCE, it predated Alexandria as the main trading port for the region by several centuries. Furthermore, its location near the Canopic Mouth of the Nile made it a bustling hub for international commerce.

The legendary place that this sunken city held within history was, until very recently, confined only to ancient texts and rare inscriptions found on land. According to the Greek historian Herodotus, a great temple was built here to mark where Heracles first set foot on Egyptian ground. The ancient Greeks later honored this story by naming the city Heracleion, after the great, half-immortal hero. Herodotus also claimed that Helen of Troy and her lover Paris visited Thonis-Heracleion before the Trojan War. Other accounts claim that it was, in fact, Menelaus who accompanied Helen. The Greek poet Nicander (2nd Century BCE) even wrote that a viper bit a helmsman of Menelaus known as Canopus on the sands of Thonis.

The Sinking of Thonis-Heracleion

Although Thonis-Heracleion was superseded by Alexandria during the 2nd Century BCE, its true downfall came in the form of a series of natural disasters. Weakened by earthquakes, tsunamis, and floods, the city was finally consumed by the sea after the ground succumbed to soil-liquefaction at the end of the 2nd Century BCE. Within a matter of moments, the hard clay of the central island turned to liquid, and the buildings upon it rapidly collapsed into the water. The final vestiges of ancient Egypt’s once-great port city finally sank beneath the waves by the end of the 8th Century. With the disappearance of the last, crumbling remains of Thonis-Heracleion, the physical remnants of the underwater city were in danger of fading from history.

The chain of events that led to the rediscovery of ancient Egypt’s most enigmatic underwater city started in 1933. While flying over Abu Qir Bay, a perceptive RAF commander noticed the ruins lying beneath the water. At the time, Thonis and Heracleion were thought to be two distinct and separate mainland cities by most historians. An entirely new era of offshore research was initiated by that pilot’s discovery.

Starting in 1996, the most significant research project over the 11 by 15 kilometer area in the western part of Aboukir Bay was undertaken by archaeologist Franck Goddio and his team. In cooperation with the Egyptian Supreme Council of Antiquities, a survey-based approach was adopted to locate, map, and excavate parts of the underwater city. Initially, side-scan sonar was utilized to establish the changing depth of the ocean floor. This entailed directing pulses of sound energy at the seabed in order to analyze the resulting echo. A nuclear magnetic resonance magnetometer was then used to detect localized anomalies in the earth’s magnetic fields. This enabled the identification of geological fault lines caused by the weight of the largest and heaviest objects upon layers of sediment, which ultimately caused them to fracture.

After years of tireless mapping in murky water, the team realized that Thonis and Herecleion were one and the same city. Then, in 2000, with the most promising excavation spots identified, the first major discoveries were made.

Incredible Discoveries From Thonis-Heracleion

While no more than 5% of the city’s total area has been explored by archaeologists, excavations have revealed numerous rich and fascinating finds. Each of these discoveries has led to the conclusion that the submerged city’s period of major activity ran from the 6th until the 4th Century BCE. Artifacts that reflect the city’s former grandeur and glory include colossal ruins, such as the incomplete statues of the god Serapis and the queen Arsinoe II. A devastated Greek temple, ancient granite columns, an underground tumulus, inscribed stele, and other architectural elements have all been found in abundance.

The city’s main temple of the god Amun-Gereb has also been discovered and has revealed hundreds of mostly intact ritual artifacts among the building blocks and columns. The Doric columns of a nearby circular Greek temple were also discovered across from this main temple. It was one of many to demonstrate the spiritual favor bestowed upon Thonis-Heracleion.

Among the smaller discoveries, treasures of bronze, ceramic, and gold have also been found, including bronze coins dating from the reign of Ptolemy II. Many of the bronze artifacts also included statues of Osiris, the revered god of fertility in ancient Egypt. Even a wooden sofa used at banquets and wicker fruit baskets has been uncovered.

Around seventy ancient vessels have also been found, including an ancient Nile river boat known as a baris. Descriptions of this type of vessel written by Herodotus in 450 BCE were found to be consistent with the one discovered in the underwater city. The wreckage of an ancient military vessel was also discovered, which was likely moored close to the huge Temple of Amun-Gereb when it collapsed. Even an eleven-meter-long sycamore vessel was found. It was most likely used in a flotilla procession during the city’s annual celebration of the Mysteries of Osiris.

A consistent feature of the city’s remains is the cross-cultural interplay between Greek and Pharaonic societies. As well as Hellenic helmets and Cypriot statuettes found alongside their ancient Egyptian counterparts, religious artifacts perfectly illustrate this amalgamation of cultures. One such example is a 2,000-year-old stone figure of Cleopatra III. Depicted as the Egyptian goddess Isis, the Ptolemaic queen was sculpted in a way that reflects both Egyptian and Greek styles.

New Understanding of Ancient Egypt’s Enigmatic Port City

Although research is still ongoing, the underwater city of Thonis-Heracleion has already revealed so many of its tantalizing secrets. The quality and quanтιтy of material excavated demonstrates that the city experienced a golden period of opulence at its peak occupation during the 6th to 4th Century BCE. Its prosperity was no doubt fostered by the intense, international trading activities that took place. The main temple was a key focal point around which the rest of the city extended into a sprawling network of canals, islands, and islets. A bustling gateway to the Mediterranean, its numerous wharves, harbors, temples, and tower-houses were joined together by a series of bridges, ferries, and pontoons. Most of the maritime traffic coming into Egypt from the Mediterranean would have been controlled here, before goods were transported for distribution to the smaller, nearby port towns of Naukratis and Canopus.

The Underwater City of Canopus

Along with Thonis-Heracleion and Naukratis, Canopus was one of the main ports in Egypt for Mediterranean trade, prior to the founding of Alexandria. Also located in the Nile Delta, close to Thonis-Heracleion, its ruins now lie near the modern town of Abu Qir.

The exact date of the foundation of Canopus is unknown, but the name for this underwater city first appears in the first half of the 6th Century in a poem by Solon. In fact, Canopus is mentioned by numerous classical scholars, including Herodotus. The poet Nicander also describes how it was founded by Menelaus — the figure of Homeric legend — in memory of the helmsman who died there from a snakebite. The decadence of the city was even referred to by Seneca, who wrote of its notorious extravagance and vice. This reputation continued into Roman times when Emperor Hadrian seemed to have had such a good time in the city that he honored it by building a replica of part of it at his villa outside Rome.

The city wasn’t all extravagance and sin, however. It was famed for its sanctuaries of Osiris and Serapis during the Ptolemaic period in ancient Egypt. Pilgrims from far and wide visited in hopes of receiving miraculous healing. The mystical procession of Osiris that started at the Sanctuary of Heracles in Thonis-Heracleion also culminated at his sanctuary in Canopus.

Canopus succumbed to the same, watery fate that befell Thonis-Heracleion. A succession of natural disasters led to liquefaction of the ground beneath the city’s magnificent buildings, and it perished dramatically into the sea.

The Rediscovery of Ancient Egypt’s Notorious Port City

The ruins of Canopus were sighted alongside those of Thonis-Heracleion by that same eagle-eyed pilot in 1933. Following some archaeological investigations by Egyptian scholar Prince Omar Toussin between 1934 and 1940, the most significant research conducted on the city was, again, by Goddio’s team.

Investigations conducted by Goddio have revealed numerous colossal architectural elements, including limestone construction blocks and red granite columns. Structures located under almost two meters of sand appear to be the well-preserved foundations of a wall measuring 103 meters in length. Thought to be the remains of a wall surrounding a temple, its scale suggests the possible presence of the largest ancient Egyptian shrine found in the region to date. Pieces of granite inscribed with hieroglyphs are thought to be parts of the Naos of the Decades. This famous monolithic chapel was also found in part during the investigations by Prince Toussin, thus enabling modern archaeologists to fit together more pieces of the puzzle.

This underwater city has also revealed plenty of smaller treasures from ancient Egypt. Jewels, coins, and even crosses and seals from the Byzantine period demonstrate the wealth of Canopus. Fragments of statuary have also been found in abundance, including an incredible marble head of the god Serapis that dates from the Ptolemaic period. Given that such a small percentage of the total research area has been excavated to date, there can be no doubt that even more remarkable discoveries are likely to be made during the ongoing investigations of this magnificent underwater city.