A submarine is a watercraft capable of underwater operation. It is designed to navigate beneath the surface of the water, allowing it to perform various missions, including military operations, research, and exploration. Submarines can be powered by nuclear or diesel engines and are equipped with advanced technology for navigation and communication. Submarines are often used by navies around the world for defense purposes, such as surveillance and stealth attacks. They can remain submerged for extended periods, making them difficult to detect. Additionally, some submarines are used for scientific research, studying marine life and underwater ecosystems.