It´s a really har dmission often, there´s a point where you are going to be seen once at least, because i planned to use that in a future story the game would have, but either camera or army guys have to see you at least one time, so you have to reach that point with 1 alarm level at most. There are ducts too you can use to move through the ship but nothing that made you avoid entirely guards, you do need to clean the ship before escaping with the hostage, but it´s possible to do so.