Whales don't spray water through their blowholes as the entertainment industry frequently portrays and people believe. Despite being very entertaining, Pixar's Finding Nemo portrayed several inaccuracies when it comes to ocean life, especially whales.
As Finding Nemo shows and most people believe, these ocean mammals spray water through their blowholes. Actually, it's not really water.
When a whale inhales, a muscle flexes to open the path so that air can be taken in through the blowhole. The muscle then relaxes shut so that the creature can dive, sometimes remaining underwater for more than an hour with their lung capacity holding as much as 1,320 gallons of air.
When the whale returns to the ocean's surface for another breath of air, it has to first release the previous breath, which is now hot from being inside the whale's body. When the hot air hits the cool air upon exiting the blowhole, it spontaneously condenses and appears to exit in a spray of water.
Plus, Finding Nemo's humpback whale should have had two blowholes instead of one; should not have had the pendulum-shaped structure dangling in the back of its mouth; and should have digested the main characters after they fell down its throat since whales aren't built to allow the escape portrayed in the movie.