Keiko, the whale from 'Free Willy', had difficulty being freed due to his inability to hold his breath underwater for long enough

The real-life whale named Keiko, who portrayed the character Willy in the movie 'Free Willy', had difficulty being released back into the wild after the film's success. Keiko had spent 15 years in captivity and needed to be trained to live in the wild. One of the challenges was that Keiko could not hold his breath underwater for extended periods like wild whales. This made it difficult for him to adapt to the natural behaviors and survival skills necessary for a life in the open ocean.