Nuclear submarines don't exist?
What a joke. By stating that you are merely insulting your own intelligence. You basically illustrate that you are ignorant on a scale that defies belief.
You also insult the human race, implying that even though humans have developed nuclear technology, they somehow are unable to devlope a nuclear submarine.
There are infinite amount of clues that will indicate to a submariner that the are submerged. The fact that you refuse to acknowledge this only exposes how deep your cognitive dissonance is and how far you are willing to go to believe in something that even children understand.