On August 7, 2000, about 1050 mountain daylight time, a Cessna 180, N222AK, sustained substantial damage during the landing roll on runway 16, at Challis Municipal Airport, Challis, Idaho. The commercial pilot was uninjured, however, his passenger received minor injuries. The airplane is registered to and operated by the commercial pilot as a visual flight rules (VFR) personal/pleasure flight under the provisions of Title 14 CFR Part 91, when the accident occurred. Visual meteorological conditions prevailed and a VFR flight plan was filed for the cross-country flight. The flight originated from Pullman, Washington, approximately 2 hours and 30 minutes prior to the accident. There was no fire and no report of ELT activation. In a written statement, the pilot reported that shortly after touchdown, during the landing roll, the aircraft began to drift left of runway centerline. The pilot applied brakes and corrective action, however, the aircraft continued off the runway, encountered soft terrain adjacent to the runway and nosed over. The aircraft sustained substantial damage to both wings and the empennage. The pilot reported that the winds at the time of the accident were variable at 10 knots. He also reported that he had not experienced any mechanical difficulties or failures with the aircraft that may have contributed to the accident.