Nice, huh? Well, if you make this line of nodes you should add them as input to a world scale sphere, not to the planet. A lake will as well of course. But I started out making it on the planet, and the shadow make the water much darker, also the translucency. I added the foam twice, once black (surface shader) and on top white (surface shader), slightly bigger, to get the shadows in the translucent waves.
Only thing is that the 'shadow foam' isn't really a shadow.