The pilot reported that he departed for a planned 1 hour flight with 8 gallons of fuel indicated on the fuel gauges, and that the airplane’s fuel consumption averaged 4 gallons per hour. About 1 hour into the flight, and approximately 10 miles from the destination, the engine began to sputter, followed shortly thereafter by a total loss of engine power. The pilot informed air traffic control that he was running out of fuel and made a forced landing in the water about 1 mile short of his destination, which resulted in substantial damage to airplane’s hull and engine pylon. The amphibious airplane was capable of water operations; however, the pilot did not hold a seaplane rating. The pilot reported that there were no preimpact mechanical malfunctions or failures with the airplane that would have precluded normal operation and attributed the loss of engine power to fuel exhaustion.