According to the pilot, all indications were in the "normal range," and the airplane was accelerating normally during the takeoff roll into a 6- to 8-knot headwind. About halfway down the 2,400-foot turf runway, the airplane attained "2/3 flying speed," and between that point and the end of the runway, it became airborne, then settled back onto the runway. The pilot decided to abort the takeoff, and reduced power and applied braking, but then realized that the airplane would not be able to stop prior to impacting a berm located at the end of the runway. He added full power, and the airplane cleared the berm, crossed a dirt road, impacted a tree and some boulders, and came to rest in a pond. The pilot stated that it had rained earlier in the day and the runway might have still been damp. The pilot also stated that he "did not detect any mechanical malfunctions."