Stefan, why not make a custom race template? It could have features that could be turned off or on from inside the if(created) or maybe even in a function or something. It would be like:
NPC Code:
this.fastinwater=0; //0-off 1-on
this.slowinwater=0; //0-off 1-on
this.slowonland=0; //0-off 1-on
this.fastonland=0; //0-off 1-on
this.normalland=1; //0-off 1-on
this.normalwater=1; //0-off 1-on
I don't know of any more features, but this custom race would be normal on both land and water. I don't know if the way I had it is right, but I hope you see what I'm trying to get at.