The airline transport-rated pilot of the Cessna 180 float plane stated that "during what started as a normal landing, the bow of the right float submerged and flipped the plane over." The airplane came to rest inverted, and sustained a bent wing spar and firewall. The pilot report over 25,000 hours of flight experience, and 30 hours in make and model. He did not report any deficiencies with the performance and handling of the airplane.