List the causes/driving forces that affect currents in the ocean.

The ocean currents form due to several reasons. Density and temperature gradients are among the main reasons. That is especially true in deep ocean currents. Surface ocean currents often form due to the forces of the wind, giving them the characteristic clockwise spirals in the northern hemisphere and counterclockwise turn in the southern hemisphere. The Coriolis effect also has an effect on ocean currents.