Well, seems to me that it really comes down to what kind of swamp you guys want. We used to have a swamp area in my family farm, but without too much water in it, so that you couldn't see any water in it. In that case, you really didn't see any movements there, only when you tried to walk over it. You knew it was a swamp by the looks of it and by trying to step on it, but there wasn't any movements present. That would be a more or less "dry swamp" (just to put a name on it).
On the other hand, there are swamps that are a rather flooded area ("wet" swamp) with lots of mud and what-nots, where the whole thing have a waving effect as stated by Astuur: an animation similar to what we have for ocean/river but much slower.
Finally, there are the swamps that have natural gas activity ("gas" swamp), where you have the boiling effect.
So, any of the three possibilities are "real-life" possibilities. Since chuck is the graphics elder, you should state what kind of swamp you have in mind for the game, and then the animation should be made with your choice in mind. Cheers!
Edited for better text presentation.