Use the open ocean fracal for procedural terrains will give you a very real looking ocean surface.  http://users.tns.net/~mwalter1/OceanScene.pdf

For the splashes, there are a few ways to go.  Get Wabe's sea splashes from Cornucopia or get SeaVue from 3Dcommune, or postwork them.

http://www.cornucopia3d.com
http://www.3dcommune.com/

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