To me this seems like an art question rather than a programming question. The easiest way to do such a thing would be through animations and have your menu system play the animations when appropriate.
Two possibilities are Adobe Flash to make vector based graphics (which isn't a free program but there are programs like Victorian Giotto which can also create flash animations), or Blender.
Personally I would probably choose to use Blender for this task. It is cross platform, open source, and free!
Blender has an Ocean modifier.
Granted it will not be trivial to create this in any program.