Imagine a mystical underwater kingdom, where vibrant coral castles rise from the ocean floor, surrounded by shimmering schools of fish and graceful sea creatures. The scene is illuminated by the soft glow of bioluminescent plants and the gentle rays of sunlight filtering through the water's surface. Merfolk with flowing, iridescent tails swim elegantly among the coral, engaging in lively dances. In the center, a majestic sea turtle glides serenely, embodying the wisdom of the ocean depths. Capture this fantastical underwater realm in a dreamy, watercolor art style, emphasizing the vivid colors and ethereal beauty of the aquatic world.