FDC made in the Soviet Union, 1961. The text on the envelope reads:”Siberia. In the upper reaces of Yenisey”. The Yenisey is the fifth-longest river system in the world, and the largest to drain into the Arctic Ocean. Rising in Mungaragiyn-gol in Mongolia, it follows a northerly course before draining into the Yenisey Gulf in the Kara Sea. The Yenisey divides the Western Siberian Plain in the west from the Central Siberian Plateau to the east; it drains a large part of central Siberia.
It is the central one of three large Siberian rivers that flow into the Arctic Ocean (the other two being the Ob and the Lena). The maximum depth of the Yenisey is 24 metres (80 ft) and the average depth is 14 metres (45 ft). The depth of river outflow is 32 metres (106 ft) and inflow is 31 metres (101 ft).