The velocity of the wave is the frequency times the wavelength. The velocity is thus one wavelength divided by the time it takes for the wave to travel one wavelength. A non-breaking water wave can be approximated by a sine wave with a wavelength, L, a period, T, a frequency, f, and an amplitude, A. See the Math Root for information on how to write an equation for this sine wave. Picture a long linear pile of water magically frozen in place above the surface of the ocean. Release the pile.
Gravity pulls the pile down.
It falls under gravity gaining speed downward and spreading as it falls. When the crest has reached the original flat surface of the water it is travelling apidl down, it overshots this position and pushes down a trough in the water. The water from the trough also spreads to the sides creating a crest to both sides of the original pile. The original wave has spread to the side. The gravitational pul of the earth and the inertia of the motion of the water both played a role in the creation of the moving wave crest.