Foam

So there is how to the water in general, with a particle based system for better results but less greater rendering times, or follow the rest of the world and use geometry. But there are the little details which make these simulations so lifelike, things like sea-foam caused by biological matter reacting in the water, this can take many forms.

There is the general foam resting atop the ocean waves, crest foam, where foam gathers at the crest of each wave that forms and beach foam, where the wave dissipates on land. These could be individual particle systems reacting to each condition, and I am not sure how to go about creating them as the particle system would have to gather / disperse dependant on the particle system or mesh it was floating on. Don't get me started on floating yet, the math...

One possibility is to use the  Motion field in Maya's Fluid Effects, motion fields act like force-fields around objects that want to react with a particle system. There could be a possibility to use a hidden object to distort the sea-foam particles in a convincing manner.