Well howdy!
I'm a model railroader with more intrest in modeling than just the trains. There is a product we use to make scale water sceans, and I think it's what your looking for. It's called Enviro Tex and is normally used as a clear plastic coating for table tops and pictures. Us model train nuts use it to create everything from rivers to oceans. With a little practice you can make waves as it cures and it looks quite real.
Here is a link to the stuff. http://www.sculpt.com/catalog_98/CoatingMaterials/Envirotex.htm
Here is what my friend did with it. Check it out. http://www.the-gauge.com/showthread.php?t=5611
I hope this helps you out.
TrainClown