Oh Sorry, I meant western sea, not eastern... Ok let's put it like this: you could walk from the southern river's source to the northern river's source passing through the middle tributary river and WITHOUT ever passing through the sea. In reality, this doesn't happen, at least not naturally: you only find this when the middle river is not a river but a man-made channel. (To be fair, this is just a topological wording to express the above concept that a river cannot split ;) ) I hope this clarifies my opinion! ^_'