Doraemon: Nobita's Great Battle of the Mermaid King

Beneath the sun-drenched waves lies a kingdom in peril, while above, a school trip promises simple fun. This 2010 animated adventure plunges Doraemon and Nobita from their familiar suburban world into a shimmering undersea realm of ancient prophecy. When a casual visit to an aquarium connects Nobita to a mermaid princess, their summer holiday transforms into a high-stakes mission. Blending family-friendly fantasy with sci-fi wonder, the film navigates themes of friendship and environmental duty. The gang must bridge two worlds, using futuristic gadgets to protect a hidden civilization from a vengeful force, proving that courage can be found in the most unexpected depths.