Jabberjaw and the gang are safari-bound with archaeologist Dr. Acosta, who seeks the ancient treasure of Panaqua using Sao Museum's famous code disc. The sinister Octopus steals the disc not for himself.
The Brotherhood of Evil threatens the undersea world when it learns the Power Helmut, invented by Profesor Ortega, grants its wearer 's every wish. Jabberjaw accidentally runs into the Brotherhood's evil henchmen and exchanges Shelly's sombrero for the Power Helmut . The henchmen chase after Jabberjaw in order to retrieve the Power Helmut.
Hoping to capture the nation's leaders and rule the undersea lands, Commander Shark boards an ocean liner and kidnaps the Ambassador of Aquatania. Since the Neptunes were aboard the ship at the time, they are accused of the kidnapping and are ordered to return the Ambassador or go to prison.
Jabberjaw and the Neptunes, touring the undersea kingdom of Hydrabia, meet two henchmen of the evil Volton, who lives in a magic ele ctrolamp. Jabberjaw buys the lamp as a souvenir and unwittingly releases the evil energy of Voltron.
Jabberjaw and gang encounter the sinister Sculpin, who stole an unfinished time machine from Professor Thorstein, the inventor. Scul pin orders the Professor captured so that he can complete the time machine. Unfortunately, Clamhead looks just like the Professor an d is captured instead.
Jabberjaw and the gang accidentally enter the domain of Sorceress Madame Sargasso and are taken prisoner. They discover the sorceres s has electro-magnetic powers which must be fed by diamonds. Jabberjaw must save the Neptunes after she turns them into zombies to w ork her diamond mines.
Jabberjaw and his friends travel to an underwater amusement park where they encounter Dr. Cybron and Zokon, who are planning to rule the world by kidnapping the president of the Undersea Nations Organization and replacing him with a robot.
Evil Dr. Robek invents a microbe with a fantastic appetite for oil. He plans to smuggle his invention to Petrolaqua so he can coerce world leaders to capitulate or he will destroy undersea oil deposits.
Jabberjaw and the Neptunes are passengers on a tanker that is suddenly snapped up by the jaws of the Pirahna's ship. They discover a giant rocket and uncover Pirahna's plan to launch it, spreading a mist over the country.