How it works
immediately when you press "3", you will see farther with a black circle around your vision, which is black at the outside and fading coming closer into the center allowing you to see through it.
3rd person to 1st person
Note that when you use it, you will see through the eyes of your seadog, which means that you're seeing it from a lower angle. You might often find parts of your ship in the way and blocking your vision witch is why you should try to lean over railings in you're ship to see over them.