Under the sea waves at the mouth of the Ropotamo River lies the traces of the nearly 6,000-year history of the region. The ancient city, opened in 1976, was part of the third-season work of the Black Sea Map project, reported on its website at the Center for Underwater Archeology. The remains lie only 4 meters beneath the Black sea surface.

The expedition found that in the place of the studies there had been a settlement from the Early Bronze Age, marketplaces and harbors from the time of the earliest Greek colonization of the Black Sea, buildings from the early Byzantine era, the Middle Ages and the Ottoman period.

In the underwater expedition, many artifacts, mainly ceramic vessels, were found. Remains are the best-preserved harbor of antiquity, mainly due to the fact that there was no huge construction boom in the area, as in other places with underwater ports in Bulgaria. The expedition has also found nearly 40 sunken ships at different depths.