I've owned DJI P2V+, DJI 550 with both analog and digital control (Lightbridge). I'm not a novice. Yesterday I was flying over water in Hawaii, Waikiki(Ala Moana park). had another DJI Phantom (prolly 3) and another drone in close proximity to my take off/landing point. Strong signal, auto channel enabled, etc. battery completely charged No issues with control or video downlink. No digital pixelation or signal loss on control signal. Went out to about 3500 feet, parallel to shoreline, altitude 340 AGL. decided to return home, hit RTH. was returning back, all good. Had camera looking down, was looking at reef, etc from 350 feet up. Got about 800 feet away and I noted reef looked really close, like I had zoomed picture in. Only thing I recall was stopping to hover at 350 feet and went into menu to ensure front lights were turned on and object/collision avoidance was turned on (it was dusk and other idiot pilot was flying irresponsibly, too low, too fast, etc in area). When I returned to camera view after closing menu I noted how "zoomed" into water it appeare Quickly looked at altitude and noted that I was rapidly descending. . When I finally realized what was going on I was 18 feet above water.. Quickly took control, Up stick and headed to beach, which was only about 50-100 yards away to AC's 3 o'clock. Almost flew it into a palm tree, came to hover, gained altitude to 60 feet, came down beach, hovered about 20 feet away and AC immediately went into descent, like battery was under 10%. Landed safely. Battery was at 51% when i noted it was descending over water. Was just under 50% when it descended/landed near me. All of the above was determined by looking at my flight records, etc on DJI Go app, watching map, flight data replay. What caused it to decide to attempt to land 800 feet away? I used RTH on app, not on controller. Home point was not changed, according to telemetry replay. Why did it attempt to land as if battery was below 10? . I swear all lights were blinking red, like low battery upon landing, yet app and later telemetry indicated plenty of power remaining when I landed. . I'm new to Go app, but not new to monitoring aircraft, flying or DJI flight modes, RTH, etc. AC flew fine that morning at relatively same location. I had ensured I had done proper IMU and compass calibration How do I view actual telemetry data over signal ,battery, etc, rather than replay? I never received a loss of signal or any other warning, both during or prior to take off/flight. Earlier phantoms were prone to momentary power hiccups due to poor battery connection causing inaccurate low battery behavior. I ensure battery is properly inserted (firm push in, listen for audible click, give it a little tug to ensure properly latched in place). What happened? What should I check, review?