On September 5, 2000, about 1530 Alaska daylight time, a Stinson 108-3 float equipped airplane, N603C, sustained substantial damage when it nosed over during landing at the Yakutat Harbor Seaplane Base, Yakutat, Alaska. The private pilot and the sole passenger on board were not injured. The personal flight was conducted under 14 CFR Part 91, and departed Cordova, Alaska, at 1301 for Yakutat. Visual meteorological conditions prevailed at the time of the accident, and a VFR flight plan was filed. The pilot told the NTSB investigator-in-charge during a telephone interview on September 5, that while landing there was glare from the water. He described the airplane touching down, and immediately flipping over. He stated that he does not know if he dragged one of the float tips in the water, or struck an object which he could not see in the sun glare. The airplane sustained substantial damage to wings, and empennage. The pilot noted in his NTSB pilot/operator report that there was light oil on the windscreen, further obstructing his vision. He said he became aware of the oil during the leg from Cordova to Yakutat, but that engine oil pressure and temperature remained normal during the flight. Postaccident inspection by an FAA inspector revealed damage to the right float bottom from possibly impacting an object in the water.