History Series / H2OJustAddWater

* BodyHorror: When Emma in a Season 2 episode is poisoned after cutting her finger on a piece of coral, she starts mutating into a white scaled monster.

* PlayingSick: The girls had to do this in one episode because it was raining outside, however things got a bit out of hand...

* EvolvingMusic: Played with. The show used the same theme song throughout its entire run, but it was performed by a different artist each season.

Created by Creator/JonathanMShiff, it’s mostly about the girls' powers and dealing with them in [[ThisIsReality real life]]. There were initially going to be only two seasons, but due to popular demand a third season was added, with several of the characters missing and a new girl, Bella, added to replace Emma. A {{spinoff}} series, ''Series/MakoMermaidsAnH2OAdventure'', is available on {{Creator/Netflix}}. A short-lived AnimatedAdaptation, ''WesternAnimation/H2OMermaidAdventures'', is also available on Netflix.

* AdultsAreUseless: And clueless and easily distracted, and readily accept some really bizarre excuses with no question. Particularly noteworthy is Cleo's father, who fails to notice how little Cleo likes [[spoiler:Charlotte]], and does nothing to rein in Kim's brattiness.

** Charlotte spends most of series 2 trying to be nice to people, it's the main characters that are doing nasty things to her. This changes in the last four episodes.

* ClingyJealousGirl: Season 2 character Charlotte. Sophie from Season 3 is rather clingy towards her own brother.

* IJustWantToBeSpecial: When Charlotte learns that [[spoiler:her grandmother Gracie]] was a mermaid, and later discovers that Cleo, Emma and Rikki are mermaids as well, she decides that she wants to become a mermaid herself. [[spoiler:She succeeds]].

%% * JerkWithAHeartOfGold: Rikki.

* ManipulativeBastard: Charlotte may count as a minor version of this.

* ScrewTheRulesIHaveSupernaturalPowers: [[spoiler:Charlotte]] enters the moon pool alone. She develops all three of the girls' powers, and turns out to be the most talented at learning them. To put it mildly, this goes to her head to the point of nearly killing Nate, and then Cleo's favorite dolphin, Ronnie.

* HowDoIShotWeb: Each girl spends an episode wondering what her power is. When Rikki tries to find her power the first gesture she makes is the one Franchise/SpiderMan uses to shoot web.

** To various things, one being that Rikki does Franchise/SpiderMan's signature hand gesture when [[HowDoIShotWeb she tries to figure out her water power]].

** To various things, one being that Rikki does Franchise/SpiderMan's MemeticHandGesture when [[HowDoIShotWeb she tries to figure out her water power]].

''H₂O: Just Add Water'' is an Australian live-action series for preteen-to-teenage girls that has been shown in North America on Nickelodeon and Creator/TeenNick as simply ''[[MarketBasedTitle H₂O]]''. The story focuses on three friends who transform into mermaids whenever they touch water following "The ''Film/{{Splash}}'' Method" (when they are wet they turn into mermaids, and when they are dry they transform back). In the first episode, the girls are trapped in a volcanic cave on the mysterious Mako Island, where they swim in a [[GreenRocks magical pool]] during a [[{{Lunacy}} full moon]] in an attempt to swim out. The next day, they find that they [[{{TransformationSequence}} transform]] ten seconds after getting their skin wet. The trio decide to enlist Cleo's [[{{LovableNerd}} scientist best friend]] Lewis to help them understand their new predicament as they conceal their tails and newfound [[{{MakingASplash}} water powers from their friends and families.

''H₂O: Just Add Water'' is an Australian live-action series for preteen-to-teenage girls that has been shown in North America on Nickelodeon and Creator/TeenNick as simply ''[[MarketBasedTitle H₂O]]''. The story focuses on three friends who gain magical powers over water and after a trip to the mysterious Mako Island, turn into mermaids following "The ''Film/{{Splash}}'' Method" (when they are wet they turn into mermaids, and when they are dry they aren't) after swimming in a [[GreenRocks magical pool]] during a [[{{Lunacy}} full moon]].

* OverprotectiveDad: Cleo's, who seems to be afraid that his daughter will get pregnant with triplets if a boy so much as holds her hand. He slowly warms up to Lewis however, preferring that Cleo be with him than someone like [[JerkJock Nate]]. Averted with Emma's father, who is nice and normal, and Rikki's is only hostile to Zane because of a misunderstanding.

Created by Creator/JonathanMShiff, it is mostly about the girls' powers and dealing with them in [[ThisIsReality real life]]. There were initially going to be only two seasons, but due to popular demand a third season was added, with several of the characters missing and a new girl, Bella, added to replace Emma. A {{spinoff}} series, ''Series/MakoMermaidsAnH2OAdventure'', is available on {{Creator/Netflix}}. A short-lived AnimatedAdaptation, ''WesternAnimation/H2OMermaidAdventures'', is also available on Netflix.

* BareYourMidriff: All the mermaids, in mermaid form and (usually, mostly on the beach) in human form.

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* HotScientist: Dr. Denman. The characters even mention she looks more like a Baywatch actress than a scientist.
** In season 3, Cleo becomes one of these.

* SceneryPorn / RealPlaceBackground: Sponsored by Australia's Gold Coast tourist board and Sea World. Many Americans hadn't really heard of the Gold Coast before this, but wow, is it pretty.

* ShipSinking: Rikki[=/=]Zane is pretty thoroughly torpedoed in Season 3, as the relationship becomes a deconstruction of AllGirlsWantBadBoys. It also looks like this would happen to Cleo[=/=]Lewis for a while once he's PutOnABus, but is averted as he's BackForTheFinale.

* WaterTriggeredTransformation: The mermaid girls change forms when in contact with water. Even if the girls get just a little wet, like if they're taking a bath or washing their hands, it'll trigger the transformation, which leads to a lot of awkward situations.

!!''H₂O: Just Add Water'' provides examples of:

* LettingHerHairDown: The mermaid transformation does this to the girls for no apparent reason. Also Rikki is rarely shown with her hair down at first but wears it down more often as she undergoes CharacterDevelopment.
%% * LonelyRichKid: Zane.