Meet the lost city of Heracleion

Heracleion or Thonis is one of the greatest underwater archaeological discoveries made – in its heyday it was Egypt’s largest trading port.

While the lost city of Atlantis may never be found – or perhaps more likely, never existed in the first place, there are other lost submerged cities. The lost city of Heracleion (also called Thonis) in ancient Egypt may be the largest submerged city ever discovered and we are only just beginning to learn more about it.

Excavations continue and every year more and more discoveries are made about this ancient city that was lost under the waves for over a thousand years. Before it was little more than a legend that only appeared in a few ancient texts that most historians didn’t care about.


The great port city of Heracleion/Thonis

“Appearing in a few rare ancient inscriptions and texts, the city of Thonis-Heracleion was hidden for thousands of years, submerged deep under the sea.”

Dark Atlas

Of course, the city was not originally built underwater. In ancient times, it was built on some neighboring islands of the Nile Delta. There were a number of ports and was interested in canals. Its docks, temples and tower houses were connected by ferries, bridges and pontoons. It was one of the trading ports of ancient Egypt – and even the main trading port in late Egypt.

  • Harbor: At one time it was the main port city of Egypt
  • Age: Possibly as old as the 12th century BC

The city was the stuff of legends and few people thought it really existed. The legendary beginnings of Heracleion (or Thonis) date back to the 12th century BC.

It was mentioned by some of the ancient Greek historians including Herodotus, Strabo and Diodorus. Herodotus even claims that the city was visited by Paris and Helen of Troy before the outbreak of the Trojan War (they sought refuge there but were turned back by the city). The site of Troy was discovered and excavated in Turkey and can be visited today.

  • Noted: By Herodotus, Strabo and Diodorus

The city was also home to temples, including the great temple of Khonsu the son of Amun (although later the cult of Amun became more prominent). There was also the important temple of Amun-Gereb in the middle of the city.


  • Apogee: Between the 6th and 4th centuries BC

Over time, the newly founded city of Alexandria replaced Thonis as the main Egyptian port in the 2nd century BC.

Related: Sunken Treasure: Battle For San Jose’s ‘Holy Grail Of Shipwrecks’

Heraklaion/Thonis lost under the waves

Over time, the central island with the city succumbed to soil liquefaction. It had been weakened by a combination of earthquakes, tsunamis and rising sea levels. What was hard clay became liquid and the building built on it collapsed into the water.

  • Succumb: Towards soil liquefaction
  • Sinking date: Sank from the end of the 2nd century BC to the 8th century AD

It didn’t happen overnight and probably started in the late 2nd century BC, with only a few locals still calling it home in Roman times. By the time the Arabs arrived at the end of the 8th century AD, it had completely disappeared under the waves.


This former flooded town now lies 2.5 kilometers from the coast and in less than 30 feet or 9.1 meters of water. It is 32 km or 20 miles from the major Egyptian city of Alexandria.

  • Distance: 2.5 km or 1.6 miles off the coast
  • Depth: 30 feet or 9.1 meters of water

Related: The Lighthouse of Alexandria and what can be seen today

Discovery and excavation

The ruins of the town were first discovered in 1933 when the Commander of the Royal Air Force saw the ruins while flying over the bay. At that time, most historians believed that Thonis and Heracleion were different cities on the Egyptian mainland.

  • Spotted: In 1933 by the Royal Air Force
  • First dig: In 1999


Exploration of the ruins began in 1999 by French archaeologist Franck Goddio. Many finds from the ancient history of the city have been uncovered, including that of the statues of the god Serapis and Queen Arsione II.

  • Fun fact: Queen Arisone II became the “Ptolemaic King of Upper and Lower Egypt”

A stele recovered from the site shows that he was known by both his Greek and Egyptian names. Heracleion was an ancient Egyptian port city located near the Canopic mouth of the Nile on the Mediterranean Sea.

In the past two years, other temples, wicker baskets with palm fruits, statuettes of the god Osiris, wooden sofas, gold amulets, a Ptolemaic galley and other finds have been discovered and excavations of the underwater site continue today.

Most of the city remains to be explored, in 2010 a type of ancient Nile river boat was discovered, in 2019 a small Greek temple was found with treasure ships and bronze coins from the reign of Ptolemy II.

Next: Lost City Of Atlantis: 25 Things We Thought To Be True (But Are Actually False)


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