Several actors in this show made brief appearances in H2O: Just Add Water (2006) including Gemma Forsyth, Lucy Fry, and Dominic Deutscher.
Due a mess up with licenses the second half of season 2 has been added to Netflix as season 3.
During the casting process for the first season, 500 actresses auditioned for the three mermaid leads. The roles eventually went to Lucy Fry, Ivy Latimer, and Amy Ruffle.
In the series finale of H2O: Just Add Water (2006), at the graduation ceremony, right before they call Bella onto the stage, they call forth Lucy Fry (played by Lucy Fry).
Lucy Fry is the third mermaid from an 'H2O' series to subsequently play a vampire (Princess Vasilisa "Lissa" Dragomir in Vampire Academy (2014)). Claire Holt also portrayed original vampire Rebekah Mikaelson in The Vampire Diaries (2009) and then in its spin-off The Originals (2013) along with Phoebe Tonkin (Hayley) who gets turned into a hybrid Vampire/Werewolf.