International Black Sea Action Day is observed worldwide every October 31. This observance commemorates the signing of the Black Sea Strategic Action Plan in 1996, which aims to protect the Black Sea from pollution. The origins of this day trace back to April 21, 1992, when representatives from Turkey, Ukraine, Russia, Bulgaria, and Romania signed the Convention on the Protection of the Black Sea Against Pollution in Bucharest. Since then, regional events have been organized in the six member-states of the convention to promote the importance of protecting the Black Sea and to highlight its significance for the economic development of the surrounding regions. The plan was revised in Sofia, Bulgaria, on April 17, 2009, further emphasizing the collaborative efforts needed to safeguard this vital marine environment, which is home to millions of people.