shaky aerial documentary footage from a small camera positioned inside the open side doorway of a naval military helicopter, looking outward toward open ocean covered with thin fog. part of reinforced metallic doorway frame visible, rugged military aircraft interior, worn anti-slip floor. steady forward flight above very calm smooth ocean surface with minimal ripples. overcast lighting, cold desaturated tones, cinematic military reconnaissance atmosphere. within the first 2 seconds a very large dark triangular fin slowly cuts through the calm water surface. the massive structure moves steadily forward leaving long smooth disturbance lines behind. scale appears far larger than known marine animals. the fin gradually disappears beneath the surface leaving wide natural ripples. aircraft motion remains observational and stable. AUDIO natural wind, distant rotor vibration, deep low frequency rumble.