No Priming Needed: Since the pump is always submerged, it's already "primed," meaning there's no need to fill the pump or intake line with fluid before it can start. This prevents a common problem known as cavitation, where air bubbles form in the pump, causing damage.
Energy Efficiency: Pushing a fluid is more energy-efficient than pulling it, especially over long distances or from great depths. Submersible pumps don't have to work against atmospheric pressure.
Durability: The sealed design protects the motor from water and other contaminants. The surrounding fluid also helps to cool the motor, preventing it from overheating.