On May 12, 2004, about 1030 eastern daylight time, an Aviat A-1B Husky amphibian, N17MR, was substantially damaged while landing on Monponsett Pond, Halifax, Massachusetts. The certificated private pilot sustained minor injuries. Visual meteorological conditions prevailed for the flight that departed Marshfield Municipal Airport (3B2), Marshfield, Massachusetts. No flight plan was filed for the personal flight conducted under 14 CFR Part 91. The pilot stated that he flew to Monponsett Pond with the intention of practicing takeoffs and landings on the water. During the approach to the pond, the pilot noted that the winds were light and variable, which caused glassy water conditions. Prior to the landing flare, the pilot was having difficulty referencing his height above the water. Subsequently, the airplane impacted the water nose-low. The float tips submerged, and the airplane came to rest inverted. The pilot was able to exit the airplane before it sank. The pilot did not report any pre-impact mechanical malfunctions with the airplane.