A form of Involuntary Shapeshifting where the specific Transformation Cause is getting one's body drenched with water. This tends to be a property of Mermaids, who will often take a human form when outside of the water and revert to their mermaid form upon either reentering a body of water or simply getting wet.
The commonness of water makes this a useful plot device to the author. The affected character can have indirect control over their form most of the time, but the plot can just as easily take that control away.
See also Elemental Shapeshifter for someone who can transform into water and Making a Splash for someone who can control water. Compare Instant Oracle: Just Add Water! when water triggers visions. See also Kill It with Water.
Examples:
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Anime & Manga
- Crayon Shin-chan has a Fractured Fairy Tale episode based on The Little Mermaid, where the titular character and his andromorphic pig sidekick Buriburizaemon need to help a merman prince (Gender Flipped version of the original mermaid) win over the heart of a princess. Their first step is helping the prince gain legs through a Magic Potion, but the witch who made the potion for them warns of its side effects that the prince will revert to a merman if exposed to water. As luck would have it, the prince gets caught in an unexpected rain that reverts him back to a merman, right in front of the princess.
- Young mermaids in My Bride is a Mermaid transform if splashed with water, making a water gun a viable weapon on one occasion. With enough practice and focus, one can (painfully) resist this effect.
- In Princess Tutu, Ahiru turns human if she comes in contact with water, but only if she's wearing her pendant. Otherwise, she'll remain as a duck, no matter how soaked she gets.
- Jusenkyo-cursed characters in Ranma ½ will change to some specific form (female human, a variety of animals, and a few monsters) when drenched in cold water and change back in hot water.
- Saban's Adventures of the Little Mermaid sees the title character able to use a magic whistle to switch forms between human and mermaid, but she will revert back to a mermaid whenever she gets wet. Cue the villains constantly dumping things on her at the most inopportune moments.
- In Toilet-Bound Hanako-kun, Nene Yashiro ate the scale of a mermaid. As a result, she's cursed to transform into a fish whenever she's submerged in water. An omake confirms she has to take baths as a fish. If she only gets a little wet, however, she just grows scales.
- In the manga version of Tokyo Mew Mew and its 2022 anime, Mew Lettuce transforms into a mermaid when she dives into the sea because of her porpoise DNA. In the 2002 anime, the transformation is triggered by her coming into contact with Mew Aqua instead.
Comic Books
- Aquaman: After Aquaman's first battle against Dead Water, he discovers the monster is actually Jonah Kendry Payne, a normal man mutated against his will. The hero believes the transformation is triggered whenever Jonah comes into contact with water, resulting in the man being confined in a special dry chamber until the researchers can find a cure for his condition. Unfortunately, Dead Water resurfaces after Jonah is exposed to his own tears, and escapes to wreak havoc again. Subverted when a later arc establishes that Aquaman's theory was incorrect; the real trigger for the transformation turns out to be the feeling of extreme distress.
- Squadron Supreme: A variation with Amphibian: he normally looks like an Apparently Human Merfolk, but if he travels to the depths of the ocean he turns into a Fish Person in order to survive. He does transform in the water, but it's technically a Pressure-Triggered Change.
Films — Animation
- BoBoiBoy: The Movie: Bora Ra gives Adu Du and Probe a task; to feed the alien squid Kurita, and not let it get wet. Probe questions how they'd get it wet - but is interrupted when they are ejected from the spaceship and into the ocean. Kurita turns into a Giant Squid as a result.
- Luca: The sea monsters can take human form, but will turn back into their true form when they are exposed to water. Even if it's just a portion of their body that gets wet, that portion will revert.
- Song of the Sea:
- Saoirse's selkie coat turns her into a seal pup when she dives into the sea.
- Bronagh reappears to the family when she turns from a seal into a woman upon landing on a rock after Saoirse finishes singing the titular song.
Films — Live-Action
- 7 Faces of Dr. Lao: Dr. Lao presents a fish in a bowl. Whenever a fish goes out, it transforms into a terrifying sea monster. A cowboy shoots the bowl and the fish turns into a sea monster. Then the monster gets soaked in water, resulting in it turning back into a fish.
- Aquamarine: The titular mermaid is able to change her fish tail into legs during the day, but she'll turn back if her legs get wet.
- Splash: Madison turns back into a mermaid whenever her legs get wet (drying them turns them back into legs), as demonstrated in the scene where the Mad Scientist Walter sprays her with a hose.
- The Thirteenth Year: Cody's gradual transformation into a merman speeds up when in contact with water.
Literature
- Captain Underpants: Mr. Krupp, who has been hypnotized to think he is the titular underwear-clad superhero, snaps out of the hypnosis and reverts to his normal personality when he touches water. His Purple Potty dimension counterpart, Captain Blunderpants, works the opposite way; he transforms into him from the kindly alternate Mr Krupp when his face gets splashed with water.
- The titular character of Emily Windsnap transforms into a mermaid whenever she's submerged in water. The books make a point that she has to be fully submerged, so simply getting wet won't trigger the transformation.
- The Laundry Files: Ramona Random, a Black Chamber operative Bob works with in The Jennifer Morgue, is a half-mermaid (merfolk in this series being Fish People who were created by the Deep Ones to be intermediaries with humans). After taking an extended dive deep in the ocean during the climax of the book, her body starts to undergo a metamorphosis to take on more merfolk traits; when she next appears in The Annihilation Score, she now has trouble walking on land and needs to spend much more time out of the day in the water than previously.
- In Susan Dexter's The True Knight, Savrin, pushed into the river, turns into an otter until a wizard catches her and pulls her out, whereupon she turns back. Later, he pushes her in again to save her, and she turns to an otter again, and nearly drowns in her clothes. When Titch rescues her, she turns to a duck and then a salmon, trying to escape, but remembers nothing after.
Live-Action TV
- H₂O: Just Add Water: 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.
- In the Kamen Rider franchise, a young man from the future named Michal Minato transforms into Kamen Rider Aqua by letting his belt absorb water from the nearest water source during his Transformation Sequence.
- Siren (2018): Merfolk transform when in contact with ocean water, partially or entirely depending on how submerged in it they are. It specifically has to be water from the ocean; when asked why she wasn't affected by falling into a pool, Ryn merely shrugs and says "Not my water."
Toys
- Many premium Hot Wheels cars are advertised as changing color in water, even including playsets designed to pour water on them to facilitate this gimmick. Like many other toys with a similar gimmick, it's the water's temperature which causes the color switch, but as far as the packaging and advertising is concerned, it's water which causes them to change color.
- Mermaid High: The Merfriends grow their tails whenever they're in the water or get wet (even just a little wet), and their legs appear when they're dry.
- Transformers: The European-exclusive late-G1 Aquaspeeders and their Evil Counterparts Stormtroopers are teams of cars with water squirting weapons. Their unique gimmick was that the water would change the color of some of their plastic. While technically it's the temperature which causes the color switch, they're advertised as water being the catalyst for the change.
Video Games
- Pokémon: A variation with the Pokémon Castform, who changes form and Type depending on the weather. Rain causes it to turn into its Rainy Form and changes its Type to Water.
- Prince of Persia: The Two Thrones: The Prince acquires a "Dark Self" that takes over his body during times of extreme danger (though the player is still in control of the Prince), and can only change back if he touches water.
- Rune Factory 3: Pia is a mermaid who can take on a human form when dry, but her legs turn into a mermaid's tail when she gets wet. In the game, she takes on her mermaid form when it's raining outside (Oddly enough, she still can move on dry land at her normal speed as a mermaid despite claiming her tail makes it difficult to move around).
- Shantae: Some transformations turn off upon hitting water, but ones suited to water, like Mermaid and Crab, don't.
- Shantae: Risky's Revenge: Monkey
- Shantae: Half-Genie Hero: Monkey
- The Sims: Mermaids and mermen turn into humans while on land and turn back into merpeople while in the water. However, they must be fully immersed; just wading isn't enough to turn them.
- Wario Land: Getting hit by certain enemies' attacks can result in Wario becoming a zombie, a vampire, overweight or drunk. Touching a droplet or a body of water will cancel the transformation and revert him back to normal.
Web Animation
- In Episode 21 of Japanoschlampen by Coldmirror, Ass, in an obvious parody of Ranma ½, accidentally falls into a spring and is cursed to turn into a girl when wet. Ass doesn't seem to care about it that much and changes from his signature dick jokes to tit jokes.
Webcomics
- El Goonish Shive: Referenced twice in regards to Elliot's Gender Bender ability (more specifically, referencing Ranma ½). Sensei Greg dumps a bucket of water
on Elliot's head to test it, only for Elliot to shout that that's not how it works. Later on, when Ashley accidentally sees him transform, she asks him if he needs hot water to turn back.
- My Impossible Soulmate: If Nereids, like Verity, submerge themselves for an extended period of time, their lower half will transform into a tail that they can use to swim more efficiently.
- In Skin Deep, Nixie saliva causes people to grow gills while wet.
Web Original
- Looming Gaia: Mermaids, who are human girls cursed by undines, take on their aquatic form when their hair gets wet.
Western Animation
- One of the villains in James Bond Jr. had implants allowing him to transform his face. However, due to No Water Proofing In The Future, whenever he got wet, we got a mild case of Facial Horror.
- The Prince of Atlantis: In the first episode, after Jaurice dies in a submarine incident, Agata uses his magic to bring him back to life and in the process attempts to turn him into an Atlantean, like him. Instead, Jaurice becomes a hybrid who will transform into an Atlantean any time he comes in contact with water, but returns to fully human if he dries up, enabling him to live both on land and under water.
- World of Quest: Dousing the Katastrophe Brothers in water causes the three of them to merge together into a stronger hybrid form, which can be undone by pulling out the cork in the back of their head. However, they are capable of bypassing this weakness by being somewhere where it's raining, which allows them to instantly merge again seconds after being separated.
- Xiaolin Showdown: Dyris the mermaid looks like what most mermaids look like when she is in water. On dry land though, she changes into her true form which is an Eldritch Abomination. Keeping her soaked in water will render her harmless, though. Klofang even states that fighting her out of water is a bad idea.
