The Black Sea turned an unusual blue color, causing panic among residents.

A body of water in the Black Sea suddenly turned a fluorescent blue color, leaving local residents baffled.

The Black Sea water in Omega Bay near the city of Sevastopol in southwestern Crimea has turned green and experts are yet to determine the cause, Express reported. Some reports said the water changed colour after an unidentified man threw a plastic bag containing liquid into the water.

The bright green streak quickly spread in area.

The bright green streak quickly spread in size. The reason why the water was so clear all the way to the bottom is unclear. Local authorities confirmed that this was not the first time the sea water had turned this strange green in the past few weeks. Russian health authorities are investigating the cause but have not yet reached a final conclusion.

Some online commentators have suggested that the sea water discoloration is due to fishermen dumping fish medicine into the water. "I used to own an aquarium when I was young and the water always changed color when a special fish medicine was added. Judging by the number of dead birds this year, maybe someone decided to treat the fish," said an account named Masha.

According to khoahoc.tv