Unsmooth behavior of water waves I happened to come across this rather interesting picture of a very deformed (or perhaps intricate) wave. The structure looks like it illustrates a superposition of multiple waveforms, as intuitively it seems like one at least three different waves are overlapping, but I don't know enough about fluid dynamics and complex wave behavior in general to understand what exactly is going on here.
I suppose I have an intuition that liquid water should not form such shapes through multiple waves combining since it is viscous and smooth and that surface tension should prevent this from happening. The upper part/s of the wave lip is also uneven and discontinuously distributed over it's length.
So what kind of behavior is this, and why do we not seem to see it more often?

 A: For the modeling of surface wave motion there are only two restoring forces to consider: surface tension and gravity. Compared to gravity, surface tension forces are very weak and therefore have a greater influence on the regime of the smaller, capillary waves. Waves in deep water carry away the energy dissipated by shear wind forces - perhaps from a storm over the sea or lake and are unimpeded by the deep terrain. One dimensional modeling is adequate to predict their behavior. These are known as deep water waves. Once the waves reach shallower water they begin to 'feel bottom'. Viscous forces begin to draw energy from the wave. These are known as shallow water waves. At even shallower depth, near a shoreline the energy must find a way out. It builds the height of the wave (potential energy) and some is lost to traction of the terrain. In any any event fluids cannot sustain the shear forces unleashed by the wave energy so you wind up with very complex, nonlinear coupled rotational motion in 3 dimensions. 
So briefly put, it's the sudden unleashing of the wave energy in shallow water, the inability of the water to sustain shear forces in three dimensions, and the chaotic dynamics of nonlinear behavior that lead to crashing wave behavior you've illustrated.
But as Richard Feynman said one can always dig deeper, look closer and find more details.
