Is it really all that bad?
What's the difference between keeping cetaceans (whales, dolphins, porpoises) in captivity in comparison to owning pets?
Pets like dogs and cats are domesticated animals. There was never wild populations of Dalmatians or Labradoodles running around. Humans have selectively bred pets this way over hundreds of years. The majority of the animals we keep as pets depend on us to take care of them up to a certain extent.
Why do they look happy then? They're clearly smiling!
Dolphins' faces unfortunately just look that way. It's because of the animal's jaw structure. Ric 'O Barry, founder of Dolphin Project, was famously quoted saying "A dolphin's smile is nature's greatest deception. It creates the illusion that they're always happy." They can't alter it and unfortunately, even in death, always appear to have that permanent grin on their face.
How do we know they're not actually happy?
Dolphins in captivity are frequently found with stomach ulcers from stress and they display stereotypic repetitive behaviors similar to prisoners and the mentally ill.