While most boats like to stay afloat, submarines like to stay hidden under the water. Submarines are the boats that can stay underwater and also float on the water. Since they stay more under the water their design is very different from the normal ships.

Of course, the first requirement is that it has to be airtight so that when it is underwater the water must not  enter it and make a tiny swimming pool inside. Now the pressure of the sea water is very strong specially if you want to stay under the sea. So the hull of a submarine is made extremely strong otherwise the water will crush it. What is a hull? It is the main body of a ship or other vessel, including the bottom, sides, and deck excluding the masts, superstructure, rigging and engines. Submarines also use unique engines that do not require air to work as there is less air under water.

You must be wondering how does a submarine go under the water from a floating state. To do that  it has sealed compartments that open up and fill with water. With so much water, the ship becomes heavy and sinks. In order to come up the submarine has to release the water in these compartments, so the boat is lighter again and floats back up!

How does he submarine see what is going on the top of the water. They use a unique device called the periscope that can be raised out of the submarine so that the submarine crew can see what is happening outside. Sonar is also used. It is a sound system that hears what is underwater by sending out sound waves. When the sound waves hit an object, they are reflected back with a sound picture of that object.

Well, now you know a lot about submarines, but can you guess why are they even required?

They were initially used by scientists to explore the underwater. The amazing marine life that would otherwise have stayed hidden in the sea. Later, the military realized that the submarines can be used as the spies of the sea. In times of war, they can stay hidden and launch a surprise attack. Smaller submarines that are also called submersibles are used to find sunken ships and treasures. In fact, the famous cruise ship Titanic was discovered by a submersible.

Do you know what is a raised deck of a submarine?
When the submarine travels above the water, the officers can stand on it conning tower, it is called raised deck of the submarine.