i personally would like to see this in game but not as a ship you can sail but more of a ship you can fight. i propose having it as an event where you fight this behemoth much like fighting the legendary ships on assassins creed black flag and beating it gives you a high chance of getting rare gold upgrades, thus it would be a very rare occurrence (and it would give me an excuse to play the black flag legendary ship theme ). oh and if it ever was added this way it would be nice if it had its own ai so it acted smarter and generally made it that much more difficult to beat. i personally believe that while it may have not been able to show itself to the world it can show itself in this game.