Underwater World With Natalia Avseenko, The White Sea, Russia

In summer, surface water warms up to 15 °С in the central part, but remains relatively cold in the north, at 7–8 °С, due to the water exchange between the surface and the cold bottom part which is enhanced by the shallow depths in the northern parts. Deep sea (about 100 m or more) is characterised by stable temperature (–1.4 °С) and salinity (30‰). The depth distribution of water temperature is very inhomogeneous across the sea. For example, at the exit from Dvina Bay, water temperature drops to 0 °C at the depth of only 12–15 m, but the same temperature is reached at 65 m at the exit from the Kandalaksha Gulf.
History
The sea was known to the Novgorod people since at least the 11th century and was rapidly explored because of its commercial significance for navigation and coastal forests rich in fur animals. One of the earliest settlements near the sea shores was established in the late 14th century in Kholmogory, on the Northern Dvina River. From there, in 1492, a merchant fleet laden with grain and carrying ambassadors of Ivan III of Russia sailed to Denmark, marking the establishment of the first international seaport in Russia.