Environment Minister Murat Kurum said this week that 25 sea surface-cleaning and barrier-laying boats, as well as 18 other vessels, were working to prevent the spread of the mucilage. Illegal fishing and "ghost" nets would be halted and Turkey would declare Marmara a protected area by the end of 2021, he said.

Scientists say climate change and pollution have contributed to the proliferation of the substance, which contains a wide variety of microorganisms and can flourish when nutrient-rich sewage flows into seawater.

Although the coasts were mostly deserted, some people were seen swimming in the sea regardless of the outbreak. 

A recent study has revealed that the "sea snot" outbreak in the Marmara Sea has doubled in just five days.