On October 4, 2003, about 1500 eastern daylight time, a Cessna 172P, N98145, was substantially damaged when it overran the runway while landing at Sussex Airport (FWN), Sussex, New Jersey. The certificated flight instructor and the certificated student pilot were not injured. Visual meteorological conditions prevailed, and the airplane was not operating on a flight plan. The local instructional flight, which originated at Essex County Airport (CDW), Caldwell, New Jersey, was conducted under 14 CFR Part 91. According to a written statement submitted by the flight instructor, the airplane departed Essex at 1430. The weather began to deteriorate, and the flight instructor elected to land at Sussex to allow weather conditions to improve. At Sussex, under calm wind conditions, the airplane touched down about the "midfield" point on a wet, runway 03. The braking action was "nil", and the airplane hydroplaned. It then began to veer to the right, and departed the end of the runway. Once the airplane was off the runway, the instructor regained directional control, and he steered it to the right to avoid a road, but encountered grass and mud. The student pilot then applied heavy brake pressure, which resulted in the airplane turning harder to the right, and the nose landing gear was forced deep into the mud. The left wing tip and the propeller then struck the ground. The instructor also reported that the brakes operated normally while taxiing at Essex, as well as during the airplane's recovery at Sussex. According to a Federal Aviation Administration (FAA) inspector, the student pilot was on his second flight. The flight instructor was at the controls with the student pilot during the approach and landing, and was also talking the student through the maneuvers. The flight instructor also advised the inspector that the approach and landing may have been at airspeeds higher than normal. Runway 03 at Sussex was 3,499 feet long and 75 feet wide, and had a displaced threshold of 1,100 feet. The weather reported at Sussex, at 1453, included winds from 210 degrees true at 4 knots, 10 miles visibility in light rain, a scattered cloud layer at 1,400 feet, an overcast cloud layer at 1,900 feet, temperature 52 degrees Fahrenheit, dew point 50 degrees Fahrenheit, and a barometric pressure of 29.97 inches of mercury.