Flying my P3P today over a saltwater marsh, demonstrating the streaming video capability to a couple of neighbors. Drone was at a stationary hover of approx. 180 ft., about 700 ft. away from me. I was yawing the drone slowly counterclockwise when suddenly it experienced some sort of catastrophic failure and plummeted into the creek. It happened so suddenly and unexpectedly I was shocked. I saw a brief "rotor over speed" warning and the video showed the aircraft tumbling out of control. Searched for the aircraft via boat but was unable to recover it. Any idea of what could of occurred? Drone was reliable and had experienced no mechanical or firmware issues. I'm mourning the loss of my drone. It had approx. 10 hours flight time on it.