On November 26, 1995, about 1255 atlantic standard time, a Cessna 172E, N3608S, collided with the ground during a forced landing, at Lajas, Puerto Rico. The airplane was operated by the owner/pilot under the provisions of Title 14 CFR Part 91, and visual flight rules. Visual meteorological conditions prevailed. A flight plan was not filed for the solo, instructional flight. There were no injuries to the student pilot, the sole occupant, and the airplane was substantially damaged. Origination of the flight was Mayaguez, Puerto Rico, about 1230, on the same day. The pilot reported that the engine malfunctioned, for unknown reasons. A forced landing was made in a ranch field, which resulted in substantial damage to the airplane. During a conversation with the FAA FSDO inspector handling this case, he stated that when he reached the accident site, it was raining. He said they removed the wings after the crash, and drained fuel from the fuel cells. A fuel examination statement recieved from this FAA Inspector indicated approximately three hours of fuel were remaining in the fuel tanks. It also indicated water was found in the fuel strainer and carburetor bowl. A fuel tank sample and records check at the FBO where the airplane was last fueled before the accident showed no presence of water.