The film starts with Elina flying through the air, still having trouble believing that she has wings. She is soon sought out sa pamamagitan ng a juvenile sea-butterfly fairy who witnessed Nalu, the merprince Elina had befriended in the nakaraan movie, being kidnapped sa pamamagitan ng several of Laverna's goblin-like Fungi at the Crystal Cove. She was unable to intervene but Nalu was able to send her to find Elina for help.
Laverna, who was banished to the Bog of the Hinterlands sa pamamagitan ng the Enchantress' magic, is seeking the Immunity Berry - a berry that makes whoever eats it immune to all magic, past, present and future. Nalu knows where to find the berry, and so she has sent her Fungi to recover it.
Fungus Maximus, the leader of the Fungi, threatens to pour a bottle of magical poison into the ocean to destroy Mermaidia if Nalu does not lead them to the berry. Nalu reluctantly agrees, and the Fungi take him away with them underwater. Elina arrives at the Crystal Cove a short time after this, accompanied sa pamamagitan ng her companion Bibble. She finds no trace of Nalu, but encounters a mermaid named Nori. Nori had planned to meet Nalu at the cove and is unaware of the reason for his absence. When Elina tells her of the kidnapping, Nori insists on going to rescue the prince herself. Elina uses magical seaweed to breathe underwater and follows. Meanwhile, Nalu has delayed the Fungi in their quest sa pamamagitan ng leading them to a place in the ocean called the Carousel of Confusion, where people forget what they’re doing. This allows him to direct them in circles for a long time before Fungus Maximus finally catches on.
Elina soon reaches Mermaidia and catches up with Nori, who has been unsuccessfully attempting learn the location of the oracle Delphine so that Nori can ask her where to find Nalu. The only people who know the location of Delphine are the merfairies, who are too childlike to take any situation seriously and so are nearly impossible to speak with. Merfairies do settle down enough to converse with when entertaining guests in their above-water homes, however, and so Elina is able to visit them and convince the merfairies to give her the location. Delphine is disguised as the fairy ferry Shellie, a large snail-like creature who takes travellers across a river at the edge of Mermaidia.
Having proven her usefulness to Nori, the mermaid reluctantly agrees to let Elina accompany her - "as long as you can keep up with me." Nori easily out-swims Elina, but Elina takes to the air and skims along just above the waves to make the race madami even. The two reach Delphine together and Elina impresses Nori with her flying, prompting her to finally begin dropping some of her hostility. The two of them ask her for Nalu's location but Delphine won't tell them directly, saying that they first have to prove themselves. She tells them to travel to the bottom of the Depths of Despair to find the Mirror of the Mist, which will lead them to him. She warns that the two of them will have to rely on one other to make it, and that Elina will have to sacrifice; the Depths of Despair are too dangerous for a weak swimmer so Elina will have to trade her wings for a mermaid's tail. Elina refuses, having just gained wings recently after a lifetime without.
Delphine gives Elina a magical pearl kuwintas that will allow her to change her mind later. Using the kuwintas is not without risk, though. When the necklace's magic is invoked the pearls turn blue and then begin slowly turning white again, one at a time. If the user is out of the water when the last pearl turns white she will return to her original form, but if she's still underwater she becomes a mermaid forever. The two then head to the Depths of Despair together.
The Depths of Despair is a dark vertical shaft in the ocean floor. The two of them begin swimming downward but Elina is unable to progress against the powerful currents flowing through the shaft. Nori presses onward, telling Elina to wait for her, but is soon entrapped sa pamamagitan ng the fronds of one of the hostile sea plants growing on the shaft's walls. Elina can't reach her to rescue her and ends up having to activate the kuwintas after all, turning into a mermaid. She is then able to reach Nori and free her and the two of them fend off the plants to reach the cavern at the bottom.
They find the Mirror of the Mist there in the keeping of a isda who operates it on their behalf, ipinapakita an image of Nalu hanging suspended in air sa pamamagitan ng his tail from a stone arch and creating a magical bubble for them to follow on the susunod leg of their journey. While en route the two of them discover themselves spontaneously developing matching mga tattoo on their upper arms. Nori recognizes the symbol as the "Crest of Courage," which mermaid legend says will decorate anyone strong enough to travel to the very bottom of Mermaidia.
The bubble takes them to the entrance of a cave filled with boiling hot thermal vents and dissipates. Nori recognizes the cave and realizes that at the other end is an area that matches what they saw in the Mirror of the Mist when it showed them Nalu. She assures Elina that it's possible to make it through sa pamamagitan ng properly timing one's passage with the eruption of the vents, having done it before, and leads them through. Bibble becomes stranded partway through and Nori goes back to rescue him for Elina.
Beyond the vents lies a cavern filled with a variety of sea plants bearing magical fruits, including one that causes the eater to speak backwards, one that causes all of one's hair to fall out, one that reveals the eater's true self, and one that causes the eater to sing beautifully. Bibble eats one of these last fruits. When they reach the surface they find Nalu being guarded sa pamamagitan ng Max's two Fungi henchmen and have Bibble distract them with his song while the two mga sirena leap from the water to cut the seaweed ropes holding him.
Nalu is grateful to be rescued but tells them that Max has reached the cave where the Immunity Berry grows, very near where he was being held sa pamamagitan ng the two lesser Fungi. Realizing that if Laverna were to become immune to the Enchantress' magic she would become unstoppable, the three battle with the Fungi to retrieve the berry that Max has picked. They succeed, with Elina snatching the berry and leaping out of the water at the tuktok of a waterfall just as her final blue pearl begins to turn white. Max is lurking nearby, however, and threatens to release his magical poison into the water if Elina doesn't hand over the berry. She tosses the berry to him but Max breaks his side of the bargain and drops the bottle over the edge of the waterfall anyway. Elina dives to catch it and manages to restopper it just before hitting the water at the bottom. Her last pearl finishes turning white, trapping her forever in mermaid form, and Max escapes with the berry.
The seeming defeat is soon partly reversed, however, when Nori reveals that she and Elina had swapped the Immunity Berry during the heat of the chase with a similar-looking substitute - one of the berries that reveals the eater's true self. Elina then decides to risk eating one of the true-self berries herself in the hopes of restoring herself to fairy form. She succeeds, gaining wings even madami spectacular than she'd had before. Nori and Nalu reveal their pag-ibig for each other and Elina returns to Fairytopia.
Meanwhile, in the Bog of the Hinterlands, Laverna takes a bite from what she believes to be the Immunity Berry and finds herself transformed into a frog. Furious, she swears vengeance on Elina.
Laverna, who was banished to the Bog of the Hinterlands sa pamamagitan ng the Enchantress' magic, is seeking the Immunity Berry - a berry that makes whoever eats it immune to all magic, past, present and future. Nalu knows where to find the berry, and so she has sent her Fungi to recover it.
Fungus Maximus, the leader of the Fungi, threatens to pour a bottle of magical poison into the ocean to destroy Mermaidia if Nalu does not lead them to the berry. Nalu reluctantly agrees, and the Fungi take him away with them underwater. Elina arrives at the Crystal Cove a short time after this, accompanied sa pamamagitan ng her companion Bibble. She finds no trace of Nalu, but encounters a mermaid named Nori. Nori had planned to meet Nalu at the cove and is unaware of the reason for his absence. When Elina tells her of the kidnapping, Nori insists on going to rescue the prince herself. Elina uses magical seaweed to breathe underwater and follows. Meanwhile, Nalu has delayed the Fungi in their quest sa pamamagitan ng leading them to a place in the ocean called the Carousel of Confusion, where people forget what they’re doing. This allows him to direct them in circles for a long time before Fungus Maximus finally catches on.
Elina soon reaches Mermaidia and catches up with Nori, who has been unsuccessfully attempting learn the location of the oracle Delphine so that Nori can ask her where to find Nalu. The only people who know the location of Delphine are the merfairies, who are too childlike to take any situation seriously and so are nearly impossible to speak with. Merfairies do settle down enough to converse with when entertaining guests in their above-water homes, however, and so Elina is able to visit them and convince the merfairies to give her the location. Delphine is disguised as the fairy ferry Shellie, a large snail-like creature who takes travellers across a river at the edge of Mermaidia.
Having proven her usefulness to Nori, the mermaid reluctantly agrees to let Elina accompany her - "as long as you can keep up with me." Nori easily out-swims Elina, but Elina takes to the air and skims along just above the waves to make the race madami even. The two reach Delphine together and Elina impresses Nori with her flying, prompting her to finally begin dropping some of her hostility. The two of them ask her for Nalu's location but Delphine won't tell them directly, saying that they first have to prove themselves. She tells them to travel to the bottom of the Depths of Despair to find the Mirror of the Mist, which will lead them to him. She warns that the two of them will have to rely on one other to make it, and that Elina will have to sacrifice; the Depths of Despair are too dangerous for a weak swimmer so Elina will have to trade her wings for a mermaid's tail. Elina refuses, having just gained wings recently after a lifetime without.
Delphine gives Elina a magical pearl kuwintas that will allow her to change her mind later. Using the kuwintas is not without risk, though. When the necklace's magic is invoked the pearls turn blue and then begin slowly turning white again, one at a time. If the user is out of the water when the last pearl turns white she will return to her original form, but if she's still underwater she becomes a mermaid forever. The two then head to the Depths of Despair together.
The Depths of Despair is a dark vertical shaft in the ocean floor. The two of them begin swimming downward but Elina is unable to progress against the powerful currents flowing through the shaft. Nori presses onward, telling Elina to wait for her, but is soon entrapped sa pamamagitan ng the fronds of one of the hostile sea plants growing on the shaft's walls. Elina can't reach her to rescue her and ends up having to activate the kuwintas after all, turning into a mermaid. She is then able to reach Nori and free her and the two of them fend off the plants to reach the cavern at the bottom.
They find the Mirror of the Mist there in the keeping of a isda who operates it on their behalf, ipinapakita an image of Nalu hanging suspended in air sa pamamagitan ng his tail from a stone arch and creating a magical bubble for them to follow on the susunod leg of their journey. While en route the two of them discover themselves spontaneously developing matching mga tattoo on their upper arms. Nori recognizes the symbol as the "Crest of Courage," which mermaid legend says will decorate anyone strong enough to travel to the very bottom of Mermaidia.
The bubble takes them to the entrance of a cave filled with boiling hot thermal vents and dissipates. Nori recognizes the cave and realizes that at the other end is an area that matches what they saw in the Mirror of the Mist when it showed them Nalu. She assures Elina that it's possible to make it through sa pamamagitan ng properly timing one's passage with the eruption of the vents, having done it before, and leads them through. Bibble becomes stranded partway through and Nori goes back to rescue him for Elina.
Beyond the vents lies a cavern filled with a variety of sea plants bearing magical fruits, including one that causes the eater to speak backwards, one that causes all of one's hair to fall out, one that reveals the eater's true self, and one that causes the eater to sing beautifully. Bibble eats one of these last fruits. When they reach the surface they find Nalu being guarded sa pamamagitan ng Max's two Fungi henchmen and have Bibble distract them with his song while the two mga sirena leap from the water to cut the seaweed ropes holding him.
Nalu is grateful to be rescued but tells them that Max has reached the cave where the Immunity Berry grows, very near where he was being held sa pamamagitan ng the two lesser Fungi. Realizing that if Laverna were to become immune to the Enchantress' magic she would become unstoppable, the three battle with the Fungi to retrieve the berry that Max has picked. They succeed, with Elina snatching the berry and leaping out of the water at the tuktok of a waterfall just as her final blue pearl begins to turn white. Max is lurking nearby, however, and threatens to release his magical poison into the water if Elina doesn't hand over the berry. She tosses the berry to him but Max breaks his side of the bargain and drops the bottle over the edge of the waterfall anyway. Elina dives to catch it and manages to restopper it just before hitting the water at the bottom. Her last pearl finishes turning white, trapping her forever in mermaid form, and Max escapes with the berry.
The seeming defeat is soon partly reversed, however, when Nori reveals that she and Elina had swapped the Immunity Berry during the heat of the chase with a similar-looking substitute - one of the berries that reveals the eater's true self. Elina then decides to risk eating one of the true-self berries herself in the hopes of restoring herself to fairy form. She succeeds, gaining wings even madami spectacular than she'd had before. Nori and Nalu reveal their pag-ibig for each other and Elina returns to Fairytopia.
Meanwhile, in the Bog of the Hinterlands, Laverna takes a bite from what she believes to be the Immunity Berry and finds herself transformed into a frog. Furious, she swears vengeance on Elina.
