The term for the distance between two crests of a water wave is the

Wavelength

Explanation:

A wave in general, is a disturbance that travels through a point in space. It is composed of a series of alternating peaks and valleys.

Peaks are points along the wave, where its amplitude or displacement from the rest position is maximum in a positive upward direction. These peaks are also referred to as 'crests'. Valleys or 'troughs' are points with maximum displacement in the negative downward direction.

In a water wave (or waves in general), the distance between two crests or peaks is referred to as the wavelength represented by the greek symbol, λ.