Abstract: A motor system using a totally enclosed fan-cooled (TEFC) electric motor to provide power. The motor enclosure may be sealed with a variety of sealing devices, including a double mechanical seal a single mechanical seal, a double lip seal injected with grease, a labyrinth seal, and/or a repeller positioned adjacent the motor enclosure. A release mechanism prevents the fan from creating excessive drag when the system is immersed in water. The fan cools the motor when the water level is below the motor, and the surrounding water combines with the fan to cool the motor when the water level rises to at least partially surround the motor. When the fan is at least partially immersed, the release mechanism substantially prevents the fan from imposing a load on the motor due to the surrounding water. The release mechanism can take the form of a shear key, a torque-release clutch or flexible fan blades. Alternatively, a separate fan motor may be provided for driving the cooling fan.