One day in 1999, French marine archeologist Franck Goddio was diving in Abukir Bay off the coast of Egypt.

‘The visibility under water was almost non-existant and I remember I actually hit the bottom with my head going down,’ he recalls.

Major discovery

Goddio could barely see six inches in front of his face, but he was still hopeful he was on the verge of a major discovery. For the past three years he had been conducting underwater surveys of this area of the seabed and he felt sure he was in the right place.

‘We then spent several hours excavating, removing the sediment before we found the first red-granite column,’ he says.

Goddio and his team were soon to confirm what they anticipated. They had discovered the remains of the ancient city of Canopus, a flourishing ancient Egyptian port that was swamped by the sea in the 8th century AD.

There is something of the real-life Indiana Jones about Goddio, who cuts a lean, athletic figure at the age of 69. President of the European Institute for Underwater Archaeology, which he founded in 1987, he has spent much of the past 20 years focusing his attention on an underwater area – roughly the size of Paris – off the coast of Alexandria.

Here he has discovered not only the remains of Canopus, but also another city called Thonis-Heracleion, whose vestiges now lie some four miles out to sea.

Needles and haystacks

The very fact his team managed to discover these sites amid so much ocean is an achievement in itself.

Goddio says: ‘The area of survey was huge (110sq km) and we had no land references in Abukir Bay that could indicate the direction in which we should be looking.’

Back in the 1990s Goddio and his team made several trial dives in the Bay and they soon realised there was nothing whatsover to be seen with the naked eye – except for soup-like silt and sediment. In 1996 they tried a geophysics survey, which provided an idea of where the cities’ remains might be found.

Goddio adds: ‘Thonis-Heracleion was vast. It was the port of entry to Egypt, so all trade had to go through the city. Furthermore, it possessed a temple that every pharaoh had to attend to receive their title, as universal sovereign, from the supreme god Amun. So it was very wealthy.’

Dwarfing Pompeii

The settlement was so big that Goddio estimates the team has only excavated five per cent of it so far. He makes the comparison with the Roman city of Pompeii, near Naples, famously destroyed by a volcano.

‘That is a very small city. They started archaeological excavation there in the 18th century – and it is still not excavated fully. Thonis-Heracleion covers an area that is three times the size of Pompeii.’

And while his career may seem to the uninitiated to resemble that of a famous film hero, it’s not a comparison that sits well with Goddio.

‘I am the exact contrary to Indiana Jones,’ he says. ‘I am not looking for treasure. I am looking for history. Every day we find fabulous artefacts – but a fabulous artefact can be a shard of ceramic that will tell us something about an area that we did not know. Beautiful jewellery doesn’t reveal much about a site. I get excited by historical information.’

Sunken Cities, Egypt’s Lost Worlds is at the British Museum until 27 November. For more about the exhibition, click here.