HARRY POTTER AND THE GOBLET OF FIRE

There's no need to introduce the Harry Potter franchise (unless you live under a rock, in which case I say: wow), and in the fourth installment, Harry the protagonist is required to venture into Hogwarts's lake in order to collect something important to him. In this short time, he encounters merpeople. The film adaptation gives us very brief glimpses of these completely CGI merpeople who are only very vaguely humanoid and swim in a way that is completely impossible for a person in a tail suit.