Archaeologists discover clay jars with remnants of garum, an ancient "ketchup" used by Romans. (Youtube/Screengrab)

An "exceptional" discovery of an ancient Roman cargo ship dating back to the first or second century BC has been uncovered at the bottom of the Mediterranean. The ship, which was carrying hundreds of jars, was discovered at a depth of around 160 meters (524 feet) near Civitavecchia, an Italian port city about 80 kilometers (50 miles) from Rome.

Archaeologists from Italy's cultural heritage protection police squad and scuba divers from the national superintendency for underwater cultural heritage, an organization that safeguards and manages underwater heritage sites, made the discovery.

According to the cultural heritage preservation police unit, "this exceptional discovery represents an important example of the sinking of a Roman ship which faced the perils of the sea in an attempt to reach the coast and bears witness to the ancient maritime trade routes."

Police are working to survey and safeguard the site.

The cargo ship was more than 20 meters long and was loaded with hundreds of ancient Roman jars known as amphorae. They are classified as Dressel 1 B-type jars, which are tube-shaped. It is still unknown what the jars were used for.

The Mediterranean coastline of Italy is replete with ancient underwater artifacts, which police scuba diving units patrol on a daily basis to preserve from looters.

Within a few weeks in 2021, Sicilian archeologists unearthed two ancient Roman ships, one off the coast of Palermo and the other near the island of Ustica. Both ships were carrying significant quantities of wine amphorae.

Other Roman ships have been discovered in the Mediterranean, including an almost entire warship dating from the second century BC discovered off the coast of Genoa in 2013. During a year-long investigation into stolen antiques traded on the hidden market in northern Italy, authorities were tipped off about the boat's location.

Every year, hundreds of illegally obtained ancient Roman amphorae are discovered by Italian police in the homes of art dealers.

Italian officials seized in June 2021 hundreds of unlawfully acquired archaeological artifacts dated from the sixth century BC and valued at €11 million (£9.4 million) from a Belgian collector. The roughly 800 objects of "exceptional rarity and inestimable value," which included stelae, amphorae, and other items, emerged from secret excavations in Puglia.