During my visit in the Cité des Sciences et de l'Industrie I have noticed from inside a big, long, black object outside. I was told that it is a naval submarine Argonaute, which after the end of her naval duties was given another important job - to present the life on a submarine to the civilians.
Before stepping in, we could see what parts she is composed of: Going from the aft (the back in maritime language) there is the rudder and the propeller, the backwards berth, the electrical engine section (which by the shaft is connected to the propeller), the diesel engines and generators charging the batteries. Then on the lower deck there are very heavy batteries and on the upper level the control rooms and at the bow the forward torpedos launch tubes.
It is not easy to control a submarine. It is more difficult then to control a car and similarly difficult as to control a horse. Because you can go left, right, up and down and additionally control the trim (whether you are horizontal, for example when all the crew is in the bow). To achieve this you must use all the controls on the picture above, since there is no saddle and rein.
When the submarine is submerged a few meters it is possible to see what is around without being seen. To do this a periscope must be raised. What is fantastic in the Cité des Sciences et de l'Industrieis that the periscope is really working and you can watch everything around the submarine like with binoculars.
And when you are tired of spending months at sea with all the time the same people or horses, you can always use a hatch. But if there is no emergency I advise you to wait until the submarine is in the port. And better check, before going under the sea, if you do not have claustrophobia, for example by visiting Argonaute in Paris.