An international team of sailors and scientists surveying a sector of the Black Sea for clues about how prehistoric humans responded to rising sea levels have found something much different—41 well-preserved shipwrecks spanning over a thousand years of history, from the ninth century to the 19th century.

The crew made the discovery while mapping the floor of the sea with sonar and remotely operated vehicles (ROVs). They were studying a period about 12,000 years ago when the Black Sea grew much larger, an episode that ultimately contributed to the preservation of the shipwrecks.

“When the last ice age ended about 12,000 years ago, the Black Sea was really the Black Lake,” says Jon Adams, principal investigator on the project and