I was flying up at wilson creek again today and the entire flight went uneventful until I was bringing the phantom in for a landing. I have to hand catch there as most of the ground is too sloped to land without issues. I had the phantom in a hover about 10 feet in front of me and had started to walk up to it to catch and shut down the motors. About 5 feet away, the phantom suddenly rolled 90 to the right and slammed into the rocks and slid down into the water. I immediately jumped into the freezing cold mountain water after my phantom and it was under water for maybe a total of 15 seconds, but believe me, 15 seconds feels like an eternity under those circumstances. After getting the phantom out I realized that the battery had ejected, so I went back in after the battery. Total submersion time for the battery was probably < 45 seconds. I have no idea what went wrong. I was up in the mountains where there isn't any cell, wifi, or any kind of interference that I can think of. Transmitter was verified to be in GPS mode, and since I was walking up to hand catch, my right hand was not even on the transmitter to accidentally provide any input. I did do a successful compass calibration immediately prior to the flight, and the bird flew fine for about 15 minutes prior to the crash. The only thing I can think of as a possibility is that the large granite rocks possibly interfered with the compass? Of course the video that I was recording appears to be corrupted, and I am trying everything I can think of to recover it. Also, the last second of flight data from the flytrex still shows it as having 6-7 sats for gps but a sudden increase in speed for the last second. Thanks for reading as I am doing a bit of venting. **Oh, and in climbing out of the water, I slipped and busted up my knee and my elbow just to add a bit of insult to injury.