The pilot was conducting a cargo flight from Buenos Aires-Jorge Newbery Airport, BA (AEP) to Rosario Airport. After landing, they entered the main taxiway B as authorized by air traffic control. At that moment, the crew lost visual references, the edge lights, and the centerline lights of the taxiway due to the presence of a fog bank near the apron. Under these circumstances, the aircraft veered off the taxiway and entered a drainage ditch located approximately 3.40 meters from the edge of the safety strip and 1.18 meters deep, resulting in significant damage. CAUSE: Loss of visual control of the centerline of the taxiway by the crew when crossing a fog bank, causing the aircraft to deviate and depart onto the safety strip and fall into a drainage ditch. Contributing factors: Reduced visibility due to fog banks. Incomplete/out-of-service lighting on the taxiway. Lack of attention by the crew during ground maneuvers.