An interesting look at how United States Navy submarines operate and why they are considered so vital for our defense. Submarines are a vital part of the Navy and defense of the United States. Serving on them takes a special kind of person as you can go days without seeing the sun in a small and cramped space. I was able to spend a couple of days on a submarine and it was cool for the first 24 hours. If you enjoyed this video you might also like to see How Aircraft Carriers Work.