The trail of stirred-up water left behind by a moving boat is called a wake. Motorboats leave particularly noticeable wakes because of the fast-moving propellers that form a very large amount of bubbles in the water – those are called turbulent wakes. The bubbles are filled with water vapor – as the propeller blades are moving through water at a fast speed, they leave an area of low pressure behind. And when the pressure is low, the water starts to turn into vapor. This process is called cavitation. The area of science that studies these phenomena is called fluid dynamics.
This particular picture has been taken on the Adriatic Sea. The shutter speed of the camera was 1/3200th of a second.