Well,actually making it annoying can work to some degree. Then people will only go to these maps to stay there a little while,instead of hopping town to town to buy spells and such. Also,to make it a little less boring,there could be random events. Such as a storm at sea,pirate attack,ect. Of course this could get slightly annoying,example: A player feels like playing a quest where the ship leads,but then his ship wrecks upon an unknown shore. But,as with the top,it will discourage travaling across the world to another continent in less than a minute. Also I was making the idea for fun,and implementing it in my own server to play by myself. Just to see if I could do it. I just told you guys incase you needed it.