A submersible pump is a device with a hermetically sealed motor, closely connected to the pump body. The entire assembly is immersed in the fluid to be pumped. The main advantage of this type of pump is that it avoids pump cavitation, a problem associated with the high level difference between the pump and the liquid surface. Submersible pumps push liquid to the surface instead of jet pumps that create a vacuum and rely on atmospheric pressure. Divers use surface-pressurized fluid to drive a hydraulic motor into the pipe, rather than an electric motor. In solar applications, existing pumps are used, but motors can be cycled according to delta star.