The sea stretches nearly 1,200 kilometres (750 mi) from north to south, with an average width of 320 km (200 mi). Its gross coverage is 386,400 km2 (149,200 sq mi) and the surface is about 27 m (89 ft) below sea level. Its main freshwater inflow, Europe’s longest river, the Volga, enters at the shallow north end. Two deep basins form its central and southern zones.