It is. My quickest answer would be to hit the SEARCH button, type in Ocean (and associated words), and find all the posts regarding this. But basically, if you increase the X or Z value of the seed of a Power fractal, you get stretched displacement. Attach a large, displaced, and stretched perlin PF to the water shader, and you'll have a basic ocean. If you attach another white PF (or this as a child to a non colored surface layer) between water and lake, blended by a distribution shader, you get basic 'foam' (in fact you should work on a set of PF's to get a nice pattern). Set the heights in the distribution shader. You could also use the favor heights in the surface layer. Many ways to go.
Good luck.
---Dune
