A dream of a submarine is an unusual dream. Many civilians have not boarded a submarine in real life and this theme does not exert influence in waking life. Thus the submarine has low probability of appearing in a dream.
People who have boarded a submarine, or worked in the manufacturing of one, have lasting images of this underwater vehicle. They may dream of a submarine at night as their occupation of this vehicle during the day, has carried on over into a dream at night.
A submarine is associated with nautical activities. One of these that is popularly known to the common person, is spying. If the dreamer has suspicions about being spied upon, then the submarine appears in a dream, to symbolize the nagging suspicion of being spied on.
