On July 20, 2005, about 2130 Alaska daylight time, a wheel-equipped Cessna 172 airplane, N7886G, sustained substantial damage while landing at an off airport site, about 60 miles northeast of Kenai, Alaska. The airplane was being operated as a visual flight rules (VFR) cross-country personal flight under Title 14, CFR Part 91, when the accident occurred. The private pilot, the sole occupant, was not injured. Visual meteorological conditions prevailed. The flight originated at the Unalakleet Airport, Unalakleet, Alaska, about 1830. A VFR flight plan was filed. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on July 21, the pilot reported that while flying through an area of mountain valleys and passes, en route to his destination airport, he encountered significant turbulence. He said that as the flight progressed, he saw a large thunderstorm in the distance, along his anticipated flight path, and he elected to make a precautionary landing in a grass-covered field to wait for better weather conditions. The pilot said that as the airplane's main landing gear wheels touched down, the airplane abruptly nosed over. The pilot noted that after he exited the overturned airplane, he discovered that the landing area had about 8-inches of water mixed with the grass. The airplane sustained substantial damage to the wings, fuselage, and empennage. The pilot reported that there were no preaccident mechanical anomalies with the airplane.