Why can submarines rise and fall?

On the submarine, there are several large water tanks. When the submarine is about to sink, use an air compressor to pump the air out of the iron cabinet, open the valve and let the seawater rush in. The iron cabinet is filled with water, and the weight of the submarine increases, so that it can dive to the bottom of the sea.

If you want the submarine to float, you have to squeeze out the seawater from the iron cabinet and then fill it with air. At this time, the submarine will become lighter and will slowly surface.

Submarines can also launch missiles underwater, but it is much more difficult to launch missiles underwater due to environmental restrictions.

Submarine submarine