Most of times creating a seascape scene, i'm not using the ground or a flat plane and add a regular liquid material, instead i create a procedural terrain (in the advanced function editor i choose the "ocean" function), adjust the wave length and height and then i create a mixed material - one a liquid material and the other a foam material.
That way i can control quite detailed, where i want the foam to appear - which should be mostly on the higher parts of the ocean surface, like the peaks of the waves should have most of the foamy material. To get this result i use the 'influence of environment' tab to set up the appearance in height, slope, direction sliders and using the 'smooth blending strip' in the 'material to mix' tab to make some more fine adjustments.
You could use a second copy of this ocean terrain and change some settings there, to mix it up with the first ocean terrain by changing the height, position, rotation a little bit ...
That's tuning work then ...
But that's just another way, to get some result working with water surfaces ...