The highest point on a wave is called the "crest," while the lowest point is known as the "trough." This is true for any type of transverse wave, including radio waves, microwaves and waves in water.
In water, the waves are caused by the forward motion of energy moving through the water, not by the water itself moving forward. The individual water molecules affected by the wave move in a circular pattern due to the movement of each successive wave. The distance between each successive wave, measured from crest to crest, is known as the wavelength, while the distance from the trough to the crest is the wave height.