You could also turn this into a command like dig, doorbash, etc
swim <direction>
swim east; swim east, etc
That way if you start heading to a river/body of water and try to WALK it says somethign like, "You would have to swim to get there." similar to DIG
You don't always doorbash (if you have the skill trained) when you try to walk into a closed/locked door do you?
No difference to me whether or not this idea, config or otherwise, comes in....just adding ideas/choices.
Later
Jake