The pilot was practicing various flight profiles over a pond in his helicopter. After completing the first profile, he began a profile that included a normal takeoff, a 10-ft hover, an acceleration to 40 kts, a climb to 50 ft above ground level, then a return to a 10-ft hover. On the pilot’s second attempt at this maneuver, when decelerating and descending back down to a 10 ft hover, the helicopter descended too low. The front skids caught the water and the helicopter descended into the pond, substantially damaging the tail rotor assembly and the main rotor blades. The pilot reported that there were no preimpact mechanical malfunctions or failures of the helicopter that would have precluded normal operation. He also described that the weather and water conditions at the time of the accident were “calm and clear with no wind ripples on the water surface,” and that this produced a “mirroring effect” that hindered his depth perception.