Hi Brian,
Water seemed to me always as one of the more difficult things to visualize, besides fire and smoke—If the most realistic look is targeted.
I guess the standard answer would be, get comfortable with RealFlow. Certainly one of the tools many people rely on.
On the other side, given your images and taking it as “look and feel” template, perhaps you animate the dolphins and find stock-footage to compose the things you like. I know it is just a sketch that you provided to improve the communication here, but what I notice is, that the enclosed bubbles on the water line make the dolphins very tiny. If you listen to all the VFX supervisors for feature films who have talked about miniatures and water, you might filter out that it is pretty difficult to get. High frame rates is one part to make it look bigger, but the water itself doesn’t scale well. So, no suggestion to take a high frame rate camera and a aquarium. from my side.
If the budget doesn’t allow for stock-footage nor for RealFlow, perhaps one of the longest supported plug-ins for water (AFAIK) is “Add The Sea”. It might has all the features your need.
http://add-the-sea.de/eng/index.php?option=com_content&task=section&id=4&Itemid=26
But also the X-Particles, for the bubbles when the dolphin dives into the water (perhaps only the back-fin).
If you wouldn’t have used the term “most realistic” I would try to find something that could simulate close to just that, but water needs a lot of attention, as we all are so used to it. Particle packages comes to mind, but before they look “most realistic” to an trained eye, it takes a while, and with that might be an overkill as well.
Check out the plug in, it seems the best mix of affordability and features—given your project and target.
My best wishes for the project
Sassi