Do submarines have to do with buoyant force?

The Buoyant force depends on the equation Fb=mfg where Fb is the buoyant force, mf is the mass of the fluid (water) that is displaced by the body and g is the Earth's gravitational constant 6.673x10-11Newton Meters squared per kilograms squared (Nm2/kg2)

Submarines use buoyant forces and gravity to move up and down with in the water. When the Buoyant force is less than the Earth's gravitational pull on the submarine, it sinks, when the buoyant force is greater than the Earth's gravitational pull on the submarine, it rises. Once the submarine is already submerged, the buoyant force is constant.

Submarines adjust the Earth's gravitational pull on it by filling the space in between the inner walls and outer walls with water and/or gasses.

With out buoyant forces, the submarine would never return to the surface of the water.