Three images of the exact same water, each with a different exposure to produce a different effect:

The image above was a single exposure, shot at 1/250th of a second.

This image is a single exposure at 1/8th of a second.

This last image is a 10 frame multiple exposure in camera, each at 1/20th of a second.

28-90mm Leica Vario-Elmarit, Nikon 800e, Lr4, Ps CS6.