H2O : Just Add Water

Rikki Chadwick, Emma Gilbert, and Cleo Sertori are three teenage Australian girls who find themselves stranded on the mysterious Mako Island,where they end up in a pool under a dormant volcano just as a full moon passes overhead, bathing the pool in light. The girls are rescued and brought back to shore, where they return to their normal lives, until discovering their lives have become anything but normal. The girls find out that ten seconds after coming into contact with water they transform into mermaids. After further experimentation, the girls also discover they have supernatural powers over water. The trio enlist the help of Cleo's friend Lewis McCartney to help them keep their secret.

How do the girls end up naked ?