Cousteau's research methods—such as blowing up a coral reef with dynamite, accidentally driving over a baby whale only to shoot it in the head a minute later, and killing sharks with a sledgehammer just because you hate them—may come off as barbaric, which they are, but times were different back then.
It is hard to imagine this was filmed 58 years ago. Some of the underwater scenes look straight from a James Bond film. We also get to witness the French divers find and explore a sunken ship where no man has ever been before. Not to mention Jojo, the fish that got too greedy and had to be locked up.
If you have even the slightest interest in marine biology, oceans, or history in general, do yourself a mighty fine favour by watching this beautiful film. It won the Academy Award and the Palme d'Or for a reason.