currents are affected by three factors. The moon pushes water away from the surface. This surface water is replaced with water that rises from deep down. Ocean currents are also affected by salt levels. When sea water enters the Arctic or Antarctic, evaporates and becomes saltier. in the tropics, the water is blown by atmospheric winds. The most well-known current is the Gulf Stream current. Since the Gulf Stream flows more quickly than other currents, ships use it to sail from west to east.