The pressure of the sea is unyielding especially if you want to stay below the surface. The hull of a submarine is made from high strength steel; otherwise, the water pressure will crush it. The thickness of the metal skin that keeps the ocean from flooding the inside the submarine is about three inches thick.
Since submarines stay more under the water more than they are on the surface, their design is a very simple shape that is based on a cylindrical shape, is completely round and has a smooth front end. While this shape is very smooth to the touch, the design is primarily made to lessen the hydrodynamic forces of the ocean while the submarine moves through the water. This round shape is continuous throughout the interior of the submarine, as all of the equipment has to fit in every nook and