Friendship is the true magic!
The time has come to bring Tritannus and Icy down. An epic battle ensues with all of the planets' forces uniting as one. Bloom and the Winx must stop Tritannus before he activates the Emperor's Throne.
A call from a fairy's cousins provokes an epic showdown between Bloom and Tritannus, with Selkies and mutants caught in the battle.
At Alfea, the students have breakfast, which was magically prepared for them. Stella comments that it is her favorite meal of the day, while Bloom, Aisha, and Musa joke that lunch, dinner, and the occasional snacking are also her favorite meals of the day. Stella merely states that she has got a healthy appetite and that she will work it off. Aisha agrees, and that the best way to do that is through dancing, saying that not only is it a good workout, it also helps to get in touch with one's true feelings. The others agree. Throughout the whole meal, Flora had been depressed as she is still bothered about the relationship between Helia and Krystal. Aisha became worried and asked if Flora was coming along, who then quickly says she will in a minute. Once Flora was alone, Krystal approaches her and asks if they could have a private talk about Helia, much to the nature fairy's surprise.
Outside, Krystal apologizes to Flora for getting in the way of her relationship with Helia. She tries to assure Flora that they are just friends, and Helia is really in love with Flora. Flora walks off unconvinced, saying she wished she could believe that.
In the school's dance studio, the Winx were doing ballet dancing, all of them performing gracefully, except for Flora, who seemed tired and would make slight slip-ups. With Aisha as she danced before the mirror, she is suddenly met with a vision of Roy, and they dance together. Back in reality, the other girls were surprised when Aisha's footwear was suddenly replaced by magical ballet shoes. Tecna wondered where they came from, and Bloom guessed it was due to the mirror. Aisha explains that the mirror has the power to sense if one opens their heart. Stella goes up next, where she is visited by a vision of King Radius and Queen Luna. She then gets her ballet shoes. Tecna gets a vision of herself and Timmy enjoying each other's company like a normal couple, and gets her ballet shoes. Musa gets a vision of the Singing Whales from her home planet of Melody, then gets her ballet shoes. Bloom gets a vision of Sky, where they held each other tenderly, then gets her ballet shoes.
Flora, seeing how all the other girls had easily gotten their magical ballet shoes, only gets even more upset and decides to leave. Bloom and the others stop her, saying that they know why she is sad and encourage her to try gain her shoes. Flora, filled with hope and a bit more happy then dances before the mirror, where she is struck with a sad thought of Helia. Suddenly, someone releases a stream of living origami birds which fly around Flora. She turned to see Helia before her. He tells her that she is the only one he truly loves and they dance together. Soon, Flora earns her ballet shoes, and she and Helia began to levitate, both dancing on air as the other girls fly dance around them.
In the Infinite Ocean, Tritannus and Icy swim through as the former rants about how he will activate the Emperor's Throne, but first, he needs a fairy who has mastered Sirenix. Icy then elects Aisha to be that fairy. Wereturn at the Winx and at Alfea's outside campus, back in their civilian outfits. At the Alfea well, Aisha gets a call from Nereus and Tressa, who tell them Tritannus is attacking the Pillar of Light with his army of mutant slaves. They needed help fast, as well as the Breath of the Ocean in order to purify the area and summon all the Selkies. This is made tough since they cannot risk killing the mutants as they are innocent people cruelly put under control. The Winx transform and head for the Pillar of Light. At the Pillar, the girls are surprised at the numerous amounts of mutants swimming about. The Winx fight their way through the swarm, limiting themselves to only using shield spells and physical blows to avoid seriously injuring the mutant slaves too much. Bloom tells Flora to get to Nereus and Tressa to pass on the Breath of the Ocean. Flora gives Tressa the gem, who then swims over to the Pillar of Light and makes the gem shine a beam at it, causing a light shockwave. Suddenly, gates began to appear, and the Selkies pour out.
A war rages with the Winx, Selkies, Nereus, and Tressa against Tritannus, Icy, and the mutant slaves. In the midst of the battle, Tritannus corners Aisha and Lemmy, but was then encountered by Nereus. As the brothers duke it out, Icy commands the mutants to go after Aisha. Nereus quickly goes to assist Aisha, but gets shot from behind by Tritannus, mortally injuring him.
Aisha was horrified and quickly swam to him, trying to get Nereus to wake up. Tritannus mocks her that it is useless as he has done for. In rage, Aisha fires off a huge energy beam that blew Tritannus and Icy away and burying them in rubble. Next, Aisha's Sirenix Guardian appears, having been summoned for by her desire to save her cousin. Aisha uses her Sirenix wish to revive Nereus. He wakes up, to Aisha's happiness. Unfortunately, Tritannus and Icy blast themselves out of the rubble and attack. Tritannus hits Aisha with a beam of magic, ensnaring her as well as absorbing her Sirenix powers. He and Icy swim off with Aisha in tow. Bloom and the others quickly pursue.
- Krystal apologizes to Flora for coming between her and Helia.
- Flora and Helia finally reconcile.
- Aisha uses her Sirenix wish to return her cousin Nereus to life.
- Tritannus captures Aisha and absorbs her Sirenix powers to activate the Emperor's Throne.
- Aisha uses her Sirenix spell, Tide of Sirenix.
- This is the first appearance of Alfea's ballet room and magical mirror.
- Aisha's Guardian of Sirenix (3D form)
- Selkies (3D form & excluding the Winx's bonded selkie)
- Alfea Gym
- Winx Club
- Aisha's Guardian of Sirenix (3D form)
- Light of Sirenix - Used by Stella against the mutants.
- Nature Punch - Used by Flora against the mutants.
- Ice Bolt - Used by Icy against Bloom.
- Igneous Protection - Used by Bloom to defend herself.
- Morphix Punch - Used by Aisha against the mutants.
- Morphix Barricade - Used by Aisha to defend herself.
- Tide of Sirenix - Used by Aisha against Tritannus and Icy.
- This is the first time we see a Sirenix guardian and Sirenix box in 3D computer animation.
- In this episode, all Selkies are seen in 3D.
- This episode marks the last 3D Sirenix transformation of this season.
- In the Nickelodeon's clip for "Battle for the Infinite Ocean", the title is "Breath of the Ocean".
- The alternative title for this episode was titled as "The Last Discovery".
- When Krystal is done apologizing to Flora, the two sit there in silence as Flora contemplates on if she believes Krystal or not, the majority of Krystal's hair is missing.
- When Stella is dancing with the Winx, a few seconds before she got her dancing shoes, her bangles are purple, red and dark purple but when she says "yeah!", her bangles are purple, orange and pink.
- When Tressa and Nereus call Aisha, they are in 2D but the mutants are in 3D.
- When Aisha finishes her phone call and Stella asks "how were they going to do that?", Flora's bangle is missing.
- When Aisha uses her Sirenix spell, her voice is heard but her lips do not move.
“You are such a sneak Icy!”
“I'll make you sorry you said that, once I'm Empress!”
“Ha! Like that's going to happen!”