During preproduction, each girl that would be a mermaid during the season would get a molding done of her legs so they could make the mermaid tails for the scenes where they are in mermaid form. Before they were able to swim with the tails on, they had to go through a rigorous training process to get their bodies ready for the extra weight of the tails. They also learned breath holding exercises to help them with holding their breath underwater for long periods of time.