Doraemon: Nobita and the Castle of the Undersea Devil

During their summer vacation, Nobita and his friends embark on an underwater adventure in the Pacific Ocean. Jaian and Suneo borrow Doraemon’s submarine and set off across the Atlantic in search of a sunken treasure ship. As they explore, the environment gun Doraemon gave them for protection starts losing power, leaving them exposed to the dangers of the deep. Luckily, they’re saved by a group of sea creatures, who turn out to be inhabitants of the underwater kingdom of Mu. However, Doraemon and his friends are soon captured by these mysterious beings. They learn that Mu’s rival kingdom, Atlantis-now ruled by robots-has mistaken a volcanic eruption for an attack and is preparing to launch nuclear weapons at the surface world. With the help of a young boy from Mu, Nobita and his friends try to stop the robots, but they’re quickly overpowered and captured. Just when all seems lost, Doraemon’s submarine makes a final, heroic sacrifice, destroying the central computer controlling the robots and their weapons. After saving the world, the group returns to Mu as celebrated heroes.