Create a 5-second cinematic underwater adventure video based on the provided reference image. The white cat and the golden retriever are the two main characters. Preserve their exact visual identities from the reference image throughout the entire video: their faces, fur colors, body proportions, expressions, diving masks, oxygen tanks, harnesses, equipment, and overall appearance. Do not redesign or transform either animal. The scene takes place in a beautiful tropical ocean with clear blue water. Sunlight filters down from the surface, creating natural shimmering caustic light and soft volumetric rays. Small bubbles and suspended particles drift naturally through the water. The two animals are happily swimming forward together, enjoying their underwater adventure. Their swimming should feel playful, relaxed, and natural, with realistic underwater buoyancy and gentle movement of their fur and equipment. At the beginning of the video, several colorful tropical fish swim across the extreme foreground, very close to the camera. They pass between the camera and the cat and dog, briefly obscuring parts of them as they move naturally through the frame. The fish create a lively and cheerful sense of underwater exploration. The cat and dog may briefly glance toward the fish, but they remain relaxed and continue swimming forward. As the scene progresses, the tropical fish gradually move away from the foreground, allowing the two main characters to become clearly visible again. The camera continues to move smoothly with them, maintaining the feeling that the viewer is accompanying them on their underwater adventure. Meanwhile, an enormous and extremely faint silhouette begins to appear far behind the two animals in the deep blue background. At first it should be so subtle that the viewer may not immediately recognize what it is. The silhouette slowly becomes more defined as the scene progresses, revealing the unmistakable shape of a gigantic shark. The shark must remain very far behind the cat and dog. It should be vastly larger than both animals, creating a dramatic sense of scale, but it must never approach them, attack them, chase them, or interact with them. The most important visual concept is that the viewer notices the gigantic shark before the two animals do. The cat and dog remain completely unaware of the shark and continue their cheerful exploration as if nothing unusual is happening. Do not make either animal suddenly look backward toward the shark. Do not make them react with fear. Near the end of the video, the camera subtly pulls back and reveals more of the distant underwater environment. This makes the enormous shark silhouette increasingly visible behind the two unsuspecting animals. At the very end, the shark silhouette should be clearly recognizable and dramatically enormous in the distant background, while the white cat and golden retriever remain in the foreground, still innocently swimming forward. End immediately on this humorous visual contrast: two cheerful diving animals casually enjoying their adventure while an enormous shark silently looms far behind them, completely unnoticed by the characters. Use a single continuous shot with no cuts, no transitions, and no changes of scene. Camera movement should be smooth, slow, and cinematic, gently following the two animals while maintaining a strong sense of depth between the foreground characters, the midground tropical fish, and the distant shark. Use realistic underwater physics, natural swimming motion, subtle movement of fur and diving equipment, drifting bubbles, suspended particles, sunlight rays, and underwater light distortion. The visual tone should be beautiful, playful, adventurous, and slightly suspenseful rather than frightening. The shark should feel like a humorous surprise and a cinematic visual punchline, not a horror element. Maintain strong visual continuity throughout the entire video. Preserve the identity, appearance, anatomy, proportions, fur, diving equipment, and relative positions of the white cat and golden retriever. Keep the tropical fish in the foreground during the opening portion and the gigantic shark in the distant background during the latter portion. Do not introduce additional animals as main characters. Do not transform the cat or dog into different creatures. Do not change their equipment. Do not create duplicated animals. Do not distort their anatomy. Do not make the shark appear in the foreground. Do not make the shark attack the characters. Do not make the characters notice or react to the shark. Do not use abrupt camera movements, rapid zooms, cuts, scene changes, or unrelated visual events. Audio, gentle underwater ambience, soft bubbles, subtle water movement, and faint distant ocean sounds. Keep the audio calm and playful, with no dramatic horror music or sudden loud effects.