making a model swim

since this is my first thread I don't know if I'm in the right place but here it goes.
I'm using GUI to change a model of Evil Arthas to sink in deep water and still move. like the horse is swimming. I've tried using the hydra model to do this and I also tried a custom model of EA that changed the movement to amphibious but nothing is working.
I was also going to change the height by changing the movement to flying and then adjust the height by having him enter a region but I I don't know how to do it.
At the moment I'm trying to learn JASS but it is slow going.
can someone nudge me in the right direction.
thanks

The DK model doesn't have swim animations, so it will never look like it is swimming no matter what you do. The reason the hydra and other models work for this is because they have swim animations (like an alternate animation set) and then when they go swimming the animation set automatically switches.

You'd need to get a modeler to add swimming animations to the DK model for this to work.