how submarine works?

A submarine works by controlling its buoyancy to dive and surface. It has ballast tanks that can be filled with water to make it sink or with air to make it rise. The pressure hull withstands underwater pressure, and the vessel is propelled by engines, usually nuclear or diesel-electric, which drive propellers or pumpjets. Submarines navigate using sonar systems and periscopes or photonics masts when at periscope depth. Crew members live and work inside the pressurized hull, operating the submarine and performing various missions.