Revenge of the Creature

Revenge of the Creature aka Return of the Creature and Return of the Creature from the Black Lagoon is the first sequel to Creature from the Black Lagoon, being the only 3D film released in 1955 and the only 3D sequel to a 3D film. Directed by Jack Arnold, the film stars John Agar and Lori Nelson.

Having previously survived being riddled with bullets, the Gillman is captured and sent to the Ocean Harbor Oceanarium in Florida, where he is studied by animal psychologist Professor Clete Ferguson John Agar and ichthyology student Helen Dobson Lori Nelson.Helen and Clete quickly begin to fall in love, much to the chagrin of Joe Hayes John Bromfield, the Gillmans keeper. The Gillman takes an instant liking to Helen, which severely hampers Professor Fergusons efforts to communicate with him. Ultimately, the Gillman escapes from his tank, killing Joe in the process, and flees to the open ocean. ........

Source: Wikipedia