Sunken Cities: Egypt's Lost Worlds

British Museum, London. Until 27 November 2016.

In Egypt's Nile delta at Abu Qir Bay lie the remains of two cities. In 500 BC, Canopus and Thonis-Heracleion were crucial ports for trade with Greece and Greek settlement. Even their names reflect Greek mythological figures: Kanopos, pilot of Spartan king Menelaus's ship in the Trojan War, and the hero Herakles. The cities continued to flourish until at least the late fourth century AD, through Alexander the Great's founding of Alexandria in 332 BC, the Ptolemaic period of Greek rule that ended in 30 BC, and Roman rule.

A colossal statue of Hapy, the ancient Egyptian god of Nile flooding, being raised from Abu Qir Bay. Credit: Franck Goddio/Hilti Foundation/Christoph Gerigk

At some point, however, they began to sink. By the eighth century AD, the cities were submerged several metres under the Mediterranean sea bed, their precise locations lost for centuries. In the late 1990s, they were found as part of a technically challenging and scientifically sophisticated operation by the European Institute for Underwater Archaeology (IEASM) in Paris, directed by Franck Goddio. The team used side-scan sonar, nuclear magnetic resonance magnetometers and sub-bottom profilers to reveal slices through the geological strata beneath the sea bed, allowing them to begin partial excavation. Divers uncovered buildings, massive sculptures and a huge range of objects, from bronze incense burners to gold jewellery. More than 750 ancient anchors and 69 ships were also detected in the ooze, most of them from the sixth to second centuries BC, in Thonis-Heracleion's harbour.

An exhibition of this extraordinary trove, Sunken Cities, is the first large-scale show of underwater discoveries at the British Museum in London, and the most complete presentation of this complex Egyptian–Greek society so far.

More than 200 IEASM finds are exhibited, denoted on the information panels by a hieroglyphic zigzag symbolizing water. Many of them were displayed in Berlin's Martin-Gropius-Bau and the Grand Palais in Paris in 2006–07, but much has been discovered since. Among the stone statues of deities and rulers in pharaonic or Greek dress is a 5.4-metre figure of Hapy, god of the Nile inundation, which greets visitors as it once greeted Greek sailors approaching the mouth of the Nile. Nearby are inscriptions in hieroglyphic and Greek on stone and gold, intricate jewellery in recognizably Greek styles and delicate lead models of votive barques used in the cult of Osiris. These exhibits are supplemented by objects from other sites, lent by a number of museums in Alexandria and by the Egyptian Museum in Cairo, as well as the British Museum's renowned Egyptian collections (notably, those from the upstream ancient Greek port of Naukratis). Ethereal silent underwater film footage strategically positioned throughout the exhibition shows divers investigating and rescuing a few key objects, including a sycamore barge of Osiris.

Ancient Egypt was not isolated, but an outward looking, influential and inclusive society.

The hybrid culture on show may surprise, and at times confuse, visitors familiar with the art and objects characteristic of earlier Egyptian dynasties found at sites such as Luxor and Abu Simbel. Says exhibition curator Aurélia Masson-Berghoff: “People sometimes assume that when two cultures mix, the essence of each is diluted and, as a result, weakened; Sunken Cities demonstrates the opposite.” She notes that ancient Egypt was not isolated, as is sometimes thought, but an “outward looking, influential and inclusive” society. This is amply borne out in the history and culture of Ptolemaic and Roman Egypt. Alexander and his friend and general Ptolemy — who became Ptolemy I in 306 BC — worshipped at Egyptian shrines; and Cleopatra and her lover the Roman general Mark Antony presented themselves as the living Egyptian–Greek deities Isis–Aphrodite and Osiris–Dionysus. A terracotta lamp with an Egyptian Isis motif, dating from the second century AD and on show from the British Museum collection, was found in far-off Roman Britain.

Ancient Egyptian science also appears. The black granite of a fascinating shrine from the fourth century BC known as the Naos of the Decades is heavily inscribed with hieroglyphs and a large figure of a lion. In submerged Canopus, it broke apart and the pieces spread far and wide: the roof ended up in the Louvre in Paris in 1817; the base and rear wall were found on site underwater in 1933 and deposited in the Graeco-Roman Museum in Alexandria. Amazingly, the IEASM team stumbled on four further pieces in 1999. Egyptologist Anne-Sophie von Bomhard examined the Naos, reconstructed after more than a millennium. Its external surfaces depict a calendar dividing the Egyptian year into ten-day sections ('decades'), connected with the successive rising of certain stars ('decans'). This proved that ancient Egyptian astrology was based on astronomical observations.

The exhibition discusses theories about why Canopus and Thonis-Heracleion sank without favouring any one cause, for lack of definitive historical or contemporary evidence. Possibilities range from tsunamis and earthquakes to floods, variations in sea level and geological subsidence, all known to have occurred in the region. There was, for instance, an earthquake in AD 796 or 797 that damaged the top section of Alexandria's Pharos lighthouse, according to ninth-century ADArab historian al-Tabari. These natural forces may have contributed to another, human-made, phenomenon revealed by core samples taken from the sediments under Abu Qir Bay: the liquefaction of the clay soils, triggered by pressure from the cities' heavy temple buildings.

According to Goddio, perhaps as little as 5% of the area around the sunken cities has been investigated. As he writes at the exhibition's end: “What we know now is just a fraction. We are still at the very beginning of our search.”