A group of divers in Israel has stumbled upon the largest hoard of gold coins ever discovered in the country. The divers reported the find to the Israel Antiquities Authority, and nearly 2,000 coins dating back to the Fatimid period, or the eleventh century, were salvaged by the authority’s Marine Archaeology Unit. The find was unearthed from the seabed of the ancient harbor in Caesarea National Park, according to a press release from the Israel Antiquities Authority.

“The discovery of such a large hoard of coins that had such tremendous economic power in antiquity raises several possibilities regarding its presence on the seabed,” said Kobi Sharvit, director of the Marine Archaeology Unit of the Israel Antiquities Authority, in the release. “There is probably a shipwreck there of an official treasury boat which was on its way to the central government in Egypt with taxes that had been collected.”

Sharvit suggested that the treasure trove of coins might have been intended to pay the members of the Fatimid military garrison stationed at Caesarea, Israel. There are also other theories as the origins of the coins. Sharvit said that the coins could have belonged to a sunken merchant ship.

“The coins are in excellent state of preservation, and despite the fact they were at the bottom of the sea for about a thousand years, they did not require any cleaning or conservation intervention,” said Robert Cole, an expert numismaticist – someone who studies currency – with the antiquities authority.

The five divers have been called “model citizens” by the antiquities organization. Had the divers removed the objects from their location or tried to sell them, they could have faced a sentence of up to five years in prison.

The oldest of the coins is a quarter dinar that was minted in Palermo, Sicily during the second half of the ninth century. The majority of the coins can be traced back to the Faimid caliphs, Al-Ḥākim and his son Al-Ẓāhir who were alive in during the eleventh century. These coins were minted in Egypt and North Africa.

“There is no doubt that the discovery of the impressive treasure highlights the uniqueness of Caesarea as an ancient port city with rich history and cultural heritage,” stated the Caesarea Development Company and Nature and Parks Authority in the release. “After 2,000 years it is still capable of captivating its many visitors … when other parts of its mysterious past are revealed in the ground and in the sea.”