On June 21, 2008, about 1015 Pacific daylight time, a Cessna R172K, N758DH, was substantially damaged during a precautionary landing after takeoff from the Big Bear City Airport (L35), Big Bear City, California. The owner/pilot was operating the airplane under the provisions of 14 Code of Federal Regulations (CFR) Part 91. The private pilot and one passenger were not injured. Visual meteorological conditions prevailed, and no flight plan was filed for the personal flight. The cross-country flight was originating at the time of the accident with an intended destination of San Diego, California. In a written statement, the pilot reported that the takeoff roll from runway 26 was longer than normal. Upon lifting off from the runway, he recalled the climb rate was about 300 to 400 feet per minute. As the airplane crossed the end of the runway, climb performance decreased and the airplane started to descend. The pilot verified the throttle and propeller control positions, advanced the mixture to full rich, and applied 20 degrees of flaps as the airplane continued to descend. He stated that due to trees and residential structures within the immediate area, he decided to initiate a controlled landing in the water as close to the shoreline as possible. Subsequently, the airplane landed tail first within the water. The pilot and passenger exited the airplane and swam to shore. Examination of the airplane by the pilot revealed that the left and right wings were structurally damaged. The pilot did not report any mechanical anomalies with the engine or airframe. He added that at the time of the accident, the airplane weighed 2,360 pounds. The airplane's maximum gross weight is 2,550 pounds. The Big Bear City Airport is an uncontrolled airport that features a single 5,850-foot-long asphalt runway oriented 080 and 260 degrees, respectively. The reported field elevation of L35 is 6,752 feet mean sea level (msl). At 1011, the Automated Weather Observation System at L35 reported winds from 260 degrees at 9 knots; visibility 10 statute miles; clear sky; temperature 25 degrees Celsius; dew point -5 degrees Celsius; and an altimeter setting of 30.38 inches of Mercury. Using the recorded weather information and airport elevation, the density altitude was calculated to be 9,100 msl feet, and the pressure altitude was calculated to be 6,328 feet msl. Using the calculated pressure altitude, density altitude, aircraft's maximum gross weight, and reported weather conditions, a representative from Cessna Aircraft Company calculated the climb rate of the airplane to be approximately 500 feet per minute at the time of the accident.