In the most successful and critically acclaimed animated film at the time of its release, a scared clownfish searches for his lost son Nemo across the ocean in Andrew Stanton and Lee Unkrich's Finding Nemo.
As of 2010, 'Finding Nemo' is currently the highest domestic and worldwide grossing G-rated film of all time.
Before any of the work started, the Pixar animators were told to do a lot of research. So the animators went on numerous field trips, research trips and even to museums to take the fish out of the bottles and take a look at them close-up. John Lasseter told each animator that they need to go take scuba diving lessons, because he believed that they can not make a movie that takes place underwater, unless each and every person has experienced it first hand.
One of the first things Andrew Stanton did was to take real life footage of things below water and things above water, and then ask the animators to try and mimic the actual shots. The result was jaw-dropping. However now they looked too real. They wanted to make it look real, but they also wanted the viewers to know that what they are watching is a make-believe world. Eventually they managed to hit the right cord between reality and cartoony.