It is also the international day of the Black Sea. 

On this day in 1996 in Istanbul (Turkey) representatives of the governments of Russia, Ukraine, Bulgaria, Romania, Turkey and Georgia signed a strategic action plan to save the Black sea. The need for such a document arose in connection with the danger of destruction of the unique natural complexes of the water territory. At the same time, it was decided to make October 31 the International day of the Black Sea.

The Black Sea is the inland sea of the Atlantic ocean basin. The Bosphorus Strait connects with the Marmara sea, then, through the Dardanelles Strait-with the Aegean and Mediterranean seas. The Kerch Strait connects the sea of Azov. From the North into the sea deeply cuts the Crimean Peninsula. On the surface of the Black sea is the water border between Europe and Asia Minor.

The sea washes the shores of Russia, Ukraine, Romania, Bulgaria, Turkey and Georgia. On the North-Eastern coast of the Black sea is not recognized by the majority of UN member States, the state of Abkhazia.

The Black Sea is an important area of transportation, as well as one of the largest resort regions of Eurasia. In addition, the sea remains of strategic importance. In Sevastopol and Novorossiysk are the main military bases of the Russian black sea fleet.

The sea area is approximately 422 000 square km. the Outlines of the Black Sea resemble the oval with the greatest axis of about 1150 km, and the Greatest extent of sea from North to South — 580 km and a maximum depth of 2210 m, the average — 1240 m.

A characteristic feature of the Black Sea is the complete (with the exception of a number of anaerobic bacteria) lack of life at depths above 150-200 m due to the saturation of the deep layers of water with hydrogen sulfide.

The Black Sea coast and the basin of rivers flowing into it are areas with high anthropogenic impact, densely populated by man since ancient times. The ecological state of the Black Sea is generally unfavorable.

Among the main factors that disrupt the balance in the ecological system of the sea can be identified:

- heavy pollution of rivers flowing into the sea, especially from fields containing mineral fertilizers, especially nitrates and phosphates. This entails a rapid growth of phytoplankton ("flowering" of the sea — the intensive development of blue-green algae), reducing the transparency of water and the death of multicellular algae.

- water pollution by oil and oil products (the most polluted areas are the Western part of the sea, which accounts for the largest volume of tanker traffic, as well as water areas of ports). This leads to the death of marine animals and air pollution due to the evaporation of oil and oil products from the water surface.

- pollution of sea waters by human waste-discharge of untreated or insufficiently treated wastewater, etc.

- mass fishing and prohibited but used bottom trawling, which destroys bottom biocenoses.

- changes in the composition of flora and fauna of the water world under the influence of anthropogenic factors (including the displacement of indigenous species by exotic species resulting from human exposure). For example, according to experts from the Odessa branch of YugNIRO, only in one decade (from 1976 to 1987) the number of black sea bottlenose dolphins decreased from 56 thousand to seven thousand individuals.

In order to protect the environment in the Black Sea area, the ACCOBAMS agreement ("Agreement on the Conservation of Cetaceans of the Black Sea, Mediterranean Sea and Contiguous Atlantic Area") was adopted in 1998, where one of the main issues is the protection of dolphins and whales.

The main international instrument regulating the protection of the Black Sea is the Convention on the protection of the Black Sea from pollution, signed by six black sea countries — Bulgaria, Georgia, Russia, Romania, Turkey and Ukraine in 1992 in Bucharest (Bucharest Convention). Also in June 1994, the Convention on cooperation for the protection and sustainable development of the Danube river was signed in Sofia by representatives of Austria, Bulgaria, Croatia, the Czech Republic, Germany, Hungary, Moldova, Romania, Slovakia, Slovenia, Ukraine and the European Union. As a result, the black sea Commission (Istanbul) and the international Commission for the protection of the Danube river (Vienna) were established. These bodies function as coordination of environmental programmes within the framework of the conventions.