The "river on the south continent"....can that be more of an ocean channel because rivers don't really run from ocean to ocean? I probably have 15 year old maps that have the same issues and it wasn't until I joined here and started really thinking about it that I learned to fear the river police If it figures prominently in your gaming sessions of yesteryear then you will just have to leave it but if it's not actually called a river then I would just say it's a narrow channel of Salt water. Of course, it's a fantasy world and you can do whatever you want with it.

I might be able to help out on it since you aren't under a crunch. Take a look at my Signature links and let me know if anything like what I have done would work for you.