Submarines dive by allowing water to expel air from their … tanks? How do they regain buoyancy in order to surface?

Question

Submarines dive by allowing water to expel air from their … tanks? How do they regain buoyancy in order to surface?

In: Engineering

Answer 1

I believe you have that backward. IIRC subs take in water (making them denser) to dive and expel the water (creating a larger air-filled space) to surface. This is the same thing that SCUBA divers do (suck in air from the tank to fill their lungs with air to surface).