A medium shot from a side angle depicts a beautiful mermaid girl with long, flowing blue hair and pale blue eyes, sitting perched upon a dark, weathered coastal rock by the sea. She is leaning back slightly, with both hands resting firmly on the stone surface to support her upper body, her gaze soft and contemplative. Her iridescent blue tail, covered in shimmering scales that catch the light, drapes elegantly over the edge of the rock into the gentle surf. The scene is set under a vast night sky where a massive, luminous full moon hangs high, casting a brilliant silver glow over the rippling ocean waves and the glistening wet surfaces of the shore. The atmosphere is serene and ethereal, characterized by a cool color palette of deep indigos and shimmering silvers, with a soft lunar glow creating high contrast and a dreamy, cinematic mood.