Underwater Submarines sink by taking in ocean water into large tanks. This weighs them down, allowing them to sink. They take in as much as they need to go as low as they want to. When they want to return, they pump out the water by pumping pressurized air into the tanks. This forces the water out, turning the tanks into floaties and boosting them back to the surface.

They became very famous during World War II. The German U-boats almost brought Britain to its knees as they sank so much British tonnage. In fact if the Germans had not decided to move their attention away the U Boats would have been able to bring them to the knees and created a Nazi lead racist world order.

How They Make Oxygen

They have specialized machines that make oxygen from ocean water. They use electrolysis, which means electricity breaks apart H20 molecules to get oxygen. These systems work for a long time. In fact in nuclear-powered submarines they can potentially remain underwater for months at a time because their energy source does not exhaust and they do not need to restock often.

Submarines Move Forward Using Propulsion

Submarines propel themselves forward through the water using propellers or jets that shoot out water. Diesel engines or even nuclear reactors can fuel these. They use a rudder, just like a ship, to turn. These vessels can move at considerable speeds. They are the ultimate war weapon. In fact during the Cuban missile crisis the world almost went to nuclear war as Russian submarines neared Cuba.