The pilot in the tailwheel-equipped airplane reported that he had performed several takeoffs and landings from the shoreline of a lake. He reported that during the takeoff roll about 25 knots airspeed, a crosswind gust from the right, pushed the airplane to the left and into the water. The left main landing gear entered the water and spun the airplane 90° to the left, and the airplane nosed over. The airplane sustained substantial damage to the right wing and rudder. The pilot reported that during takeoff the wind was out of 180° at 20 knots and gusting to 45 knots. The METAR for an airport located 4 nautical miles from the accident site reported that about the time of the accident, the wind was out of 210° at 11 knots. No gusts were reported. The pilot reported that his direction of takeoff was to the southeast. The pilot reported that there were no mechanical malfunctions or failures with the airplane that would have precluded normal operation.