The design principle of the submarine was borrowed from the swim bladder of the fish. Submarines were inspired by fish and invented. Fish have swim bladders that can go up and down, and submarines are designed and built based on the structure of fish. The submarine is closed when it is launched into the water, and there is a big cabinet inside it, which can control it to go up and down.

The swim bladder in a fish can contract or expand under muscle control. When the swim bladder is contracted, the volume of the swim bladder becomes smaller, the gas inside is expelled, the buoyancy of the water becomes smaller, and the fish sinks into the water, and vice versa. Inspired by this, the developers also installed a similar swim bladder compartment to the submarine, that is, the main ballast water tank, through the water injection, drainage to realize the submarine dive up.

Large submarines are mostly cylindrical, and usually have a vertical structure (the bridge) in the middle of the boat, which was called the command tower (command deck) in the early days, and contains communications, sensors, periscopes, and control equipment, etc. Today's deep-sea submarines or specialized submarines are also known as deep-sea submarines, or deep-sea submarines. Today's deep-sea submarines or specialized submarines often no longer have this design.

Submarines date back to Leonardo da Vinci in the 15th-16th century. He is said to have conceived the idea of a ship that could sail underwater, but this ability was always seen as evil, so he did not draw the design. Until the eve of World War I, submarines were treated as ungentlemanly weapons, and their captured crews could be punished as pirates.