THE UNSUITABLE TERRAIN (TREES AND A LAKE) ENCOUNTERED DURING A FORCED LANDING MADE NECESSARY BY THE PARTIAL FAILURE OF THE AIRCRAFT'S POWERPLANT DURING AND ATTEMPTED GO-AROUND. THE OCCUPANTS WERE ABLE TO EXIT THE AIRCRAFT BEFORE IT SANK; THE AIRCRAFT WAS SUBMERGED FOR OVER 20 HOURS BEFORE IT WAS SALVAGED FROM THE LAKE.