Travelling across the sea aboard a ship known as The Floating Palace, Sofia is in the library reading a book when the Royal Family arrives at a tropical island known as Merroway Cove for a vacation. When Sofia asks if they'll meet any mermaids, Roland and Admiral Hornpipe both tell her mermaids are not real. Also accompanying the royal family is Cedric, who is out on another scheme to take over Enchancia -- only this time, he's not after the Amulet of Avalor. He is in search of an enchanted comb known as the Mermaid Comb of Merroway Cove, that gives whoever possesses it the power to harness the ocean. He takes a boat to a cave and transforms himself into a sea monster and Wormwood into a squid.
Meanwhile, Sofia meets up with Clover and heads down to the swimming platform. Once there, they spot a Mermaid who gets trapped in a net. Sofia pulls her onto the platform and helps her get untangled. Once free, Sofia introduces herself to the mermaid who introduces herself as Oona and the two girls become fast friends. Oona is amazed by the Floating Palace which was why she came up to get a closer look. She notices Sofia's amulet glowing and when she asks her about it, Sofia tells Oona it’s enchanted. Oona tells her that the comb she's wearing is enchanted as well, but doesn't know what it's powers are because her mother refuses to tell her as she is not old enough yet. After she gets back in the water, Oona discovers her fin was injured by the net. Sofia takes off her shoes so she can get in the water and help her. The moment her feet makes contact with the water, she transforms into a mermaid. Remembering the glow her new friend saw earlier and the amulet's rule, Sofia tells Oona her amulet gives her special powers when she does good deeds. Since she helped her when she was in trouble, her amulet blessed her with the ability to transform into a mermaid. All this makes Sofia squeal with joy as she happily hops into the water. She drifts down a few fathoms until she opens her eyes and squeals "This is incredible!" and starts swimming at lightning speed before returning to the surface. With the use of her new abilities, Sofia helps Oona swim home. Meanwhile, Clover meets a seagull named Farley who tries to make off with a bag of blueberries that Clover marked as his lunch. A battle erupts between them that causes the blueberries to get spilled overboard and gets them both stuck in a lifesaver.
Meanwhile, Sofia takes Oona to the bottom of the cove and all the sights make Sofia squeal with delight. The two girls enter a shipwreck that Oona uses as her hideaway. Suddenly, a seahorse appears and calls out for Oona who tries to hide Sofia. She tells Sofia that seahorse is her friend Sven who gets very suspicious around strangers. Sven finds the two girls and then asks Oona about where she’s been and who her new friend is, stating he hasn't seen her in the cove before. Oona says Sofia is visiting from another colony and when she hurt her fin she helped her get back. When he hears this, Sven panics and says Oona needs to see the doctor right away just as an older mermaid shows up. After being told about Oona's hurt fin, the mermaid proceeds to examine her fin: It turns out her injury is so minor it can be treated with some moon kelp. Oona introduces Sofia to the mermaid who happens to be her big sister Cora, who was sent by their mother to check on her. After Cora bandages her fin and leaves, Oona begins to moan about how her sister treats her like a merbaby, which Sofia understands completely as she knows how it feels. Then, Sofia asks where the other merfolk live and Oona and Sven give her a tour of the cove.
Unbeknownst to Sofia, she and Oona are being watched by Sea Monster Cedric and Wormwood the Squid who recognize Oona's comb as the item they seek. When he spots Sofia, he is shocked because he knows she will ruin his chances of getting the comb. Suddenly, the Floating Palace appears from above and Cora shows up to tell Oona their mother wants them back at the castle. Sofia follows the two mermaids to the coral castle where she meets their mother, Queen Emmaline of Merroway Cove and her chief advisor, Plank. It turns out that the merfolk think humans are dangerous because many years ago, a ship entered the cove and tried to capture one of the colony's inhabitants and most of its people were hurt. Plank proposes that Queen Emmaline move the ship from the cove by conjuring a storm with her Trident. Cora is the only one who supports this decision but Sven and Queen Emmaline view the plan as too reckless and irresponsible because it might sink the ship. Knowing her family is on that ship, Sofia is immediately against this plan and insists on a peaceful alternative. She tells Plank and Queen Emmaline that she will go up and persuade them to move the ship. When Queen Emmaline and Plank both ask her how she would do that since they think she's a mermaid, Sofia reveals she's actually a human and the ship belongs to her family to the shock of the entire mercolony except for Oona, who knew the whole time. When Plank and Cora start acting negatively towards Sofia, both Oona and Sven swim forward and defend her by telling everyone how Sofia helped Oona when she was hurt. Sofia gives the Mermaid Queen her word that she will get the ship to leave and sadly bids Oona farewell before leaving. Oona goes after Sofia and apologizes for how everyone acted. Sofia tells Oona the only thing she's upset about is that she'll never see her again and gives her a loving hug before sadly continuing to head back to the ship.
Just then, trouble erupts for both girls. As Oona starts to head back home, Sea Monster Cedric appears and attacks her. Sofia hears Oona calling for help and dives back into the ocean to help her. Oona heads into the kelp forest but gets ambushed by Wormwood the Squid and Cedric captures her. Sofia finally arrives in the kelp forest and calls out for Oona but to no avail. Realizing the monster must've kidnapped Oona, Sofia heads back to tell Queen Emmaline what happened. Unfortunately, Plank doesn't believe her and accuses her family of kidnapping Oona and urges Queen Emmaline to use her trident to conjure a massive storm that will sink the Floating Palace. Convinced that Plank is right, Queen Emmaline gives Sofia until sundown to return her daughter or she'll use her trident to do as Plank suggested. Sven goes after Sofia because he could tell she was telling the truth the whole time. On the ship, it turns out the royal family hasn't even noticed that Sofia is gone and are only just now noticing but they all assume that she's in her room finishing her book. When Sofia gets back on board, she heads to her family and tells them about Oona's kidnapping and her mother's threat to sink the Floating Palace. Unfortunately they don't believe her and with no one else to turn to Sofia now believes its up to her and her animal friends to find and rescue Oona before it's too late. She frees Clover and Farley from the lifesaver and instructs the seagull to take to the skies and look for Oona. He finds her locked in a cage on the monster's boat and goes back to tell Sofia, Sven, and Clover. The four of them find the cave and find out the monster knows magic and wants Oona's comb. Sofia tries to rescue her but the sea monster is too powerful for her and she fails.
Sofia feels like all hope is lost, she failed to rescue Oona and knows the second the monster gets her comb there will be no telling what he'll do to her mermaid friend and her family will be drowned for a crime they never committed and she can't get more help to save her family and friend because no one will listen to her. Sven suggests going back to tell Emmaline they found Oona but Sofia refuses stating that she won't believe her. Suddenly, Sofia's amulet begins to glow summoning Princess Ariel. She tells Sofia she still has a chance to save Oona by enlisting Cora to help by showing her that she cares about Oona as much as Cora does. Soon after Ariel vanishes, Sofia manages to convince Cora to help her and the two Princesses head off to the rescue. Meanwhile, Queen Emmaline uses her trident to conjure up a storm until Sven and his family intervene before it gets too fierce. With the trident in their possession, they lead Emmaline and Plank to where Oona is being held. With Sofia and Cora working together, they successfully rescue Oona and defeat Cedric with the power of Oona's comb. The two mermaids are reunited with their mother and Plank who both apologize to Sofia for their rashness and using the trident, Emmaline stops the storm. While she does this, she is seen by Sofia's family and Admiral Hornpipe forcing them to realize that Sofia was right all along. Sofia heads back to the ship and happily reunites with her family who all apologize for not believing her. Then she takes them to meet the merfolk who all become good friends with them and Sofia and Oona are allowed to remain friends forever. Meanwhile, a defeated Cedric returns to the Floating Palace and turns himself and Wormwood back to normal.
Home Video Release
- Ariel Winter as Sofia
- Sara Ramirez as Queen Miranda
- Wayne Brady as Clover
- Tim Gunn as Baileywick
- Darcy Rose Byrnes as Princess Amber
- Zach Callison as Prince James
- Travis Willingham as King Roland II
- Kiernan Shipka as Oona
- Jodi Benson as Ariel / Queen Emmaline
- Jeff Bennett as Farley
- John Ross Bowie as Sven
- Phil Morris as Plank
- Sarah Mitchell as Cora
- Jess Harnell as Cedric the Sorcerer
- Jim Cummings as Admiral Hornpipe
- This is the second time a Disney Princess shows up in a special (Cinderella) and the second special of the show (Sofia the First: Once Upon a Princess). There are also similarities especially between these two meetings:
- Sofia covers her eyes in despair seconds before her amulet glows and a glow is seen where the summoned princess will appear.
- Both state that the amulet summoned them to help.
- The princesses (Sofia and the summon) take a stroll (or a swim) in both cases.
- The meetings include a musical number, and both hint on what Sofia should do to set things right and the one person (Princess Amber and Cora) she should converse with to get started.
- The strolls end in a doorway to a "room" where an older girl is sulking (Princess Amber and Cora).
- In the last word of the musical number the summoned princess and Sofia are in the same position in both cases, with Sofia facing the doorway and the princess right behind her, hands rested on the former's shoulders and as Sofia turns round to thank her, the princess had magically disappeared leaving behind a cloud of shimmering stars.
- As Sofia meets the girl, they respond negatively at first until Sofia declares her mission to her. Both missions also involve a confrontation with Cedric or at least Wormwood with both girls working together.
- This is the second time Sofia undergoes a magical transformation. In "Cedric's Apprentice", she became a lizard.
- This is the second time Sofia strengthens ties between her family and supernatural creatures. Before, it was the trolls in the episode "Let the Good Times Troll".
- Ariel is the fourth Disney Princess to assist Sofia.
- Ariel is the first princess to not to be seen in her redesign as she was in her mermaid form.
- When Oona asks what kind of animal Clover is, he says "I'm a Blue Ribbon Bunny," a reference to the song and the seventh episode.
- Oona, in many ways, is similar to Sofia. Both are princesses who are the youngest members of a Royal family, possess an enchanted object which gives them magical powers and have animal friends.
- This is the third time we see Cedric's true evil side instead of his usual bumbling silliness. The first was in "The Amulet and the Anthem" and the Second was in "Princess Butterfly".
- This is the second episode where Cedric doesn't go after the Amulet, the first episode was "Tea for Too Many".
- Cedric undergoes a magical transformation for the first time in the series and so does Wormwood.
- This is Cedric's last appearance in the first season.
- This is the first episode where James is seen shirtless, the second being Cool Hand Fluke
- Oona is the only one Sofia tells the truth about her amulet.
- Oona and Sven are the only ones who know the truth of Sofia's Amulet. Queen Emmaline, Plank, Cora, and the other merfolk are aware of Sofia's powers but not the source.
- This is the second time Sofia's amulet grants her a blessing. The first was Sofia the First: Once Upon a Princess.
- Sofia gains the ability to transform into a mermaid and back. This is the first time she has used this ability.
- Sofia is almost forced to reveal the truth about her amulet to her family but she is able to avoid it when she gets the idea to ask Clover for help.
- This is the only special so far that does not take place in Enchancia.
- Baileywick is revealed to be prone to sea sickness.