The sea is long and wide and has an area of ; it is the smallest sea within the countries of the former Soviet Union. The main rivers flowing into it are the Don and Kuban; they ensure that the waters of the sea have comparatively low salinity and are almost fresh in places, and also bring in huge volumes of silt and sand. Accumulation of sand and shells results in a smooth and low coastline, as well as in numerous spits and sandbanks.