Infinite Ocean

The Infinite Ocean is an underwater realm of the Magic Dimension that appears in Season 5.

Overview
The Infinite Ocean is a special realm where everything takes on another dimension and where the Pillars of the Infinite Ocean, the pillars of the foundation of all the worlds of the Magic Dimension are located. The Emperor's Throne, one of the largest sources of power of the Magic Dimension, is also found there. Infinite Ocean is also connected to each existing ocean in Magic Dimension and Earth.

The Infinite Ocean is closely associated with the power of Sirenix, as when fairies obtain Sirenix they also obtain the power to enter the Infinite Ocean, which is forever open to all Sirenix Fairies. Omnia, the Supreme Guardian of Sirenix is also the Guardian of the Infinite Ocean.

One can enter Infinite Ocean by two methods: Acquiring the Sirenix power or absorbing the powers from each gatekeeper Selkie in the whole Magic Dimension. Sirenix grants the power to open a portal to anywhere, but Selkies powers only grants access to Infinite Ocean through an Ocean Gate.

Gates
The Infinite Ocean can be accessed using the Ocean Gates.

Sirenix Fairies also have the ability to open a Sirenix Gate which allows them to access the Infinite Ocean without using the Ocean Gates.

After Tritannus had stolen the powers of all the Gatekeeper Selkies, he gained the ability to use his trident to open magical gates which allowed them to enter the Infinite Ocean.

Season 5
The new villain Tritannus, after being turned into a monster because of pollution, tried to conquer the Infinite Ocean with the help of the Trix, and the Winx had to go on a quest to find the ancient Sirenix power to fight him because their Believix powers were too weak underwater.

After he stole the powers of all the Guardian Selkies and given Daphne's Sirenix powers to the Trix, Tritannus enters the Infinite Ocean along with the Trix, his mutant servers and Daphne as his prisoner. He then established his base there.

After Tritannus had destroyed the Source of Sirenix found in Daphne's Cave in Lake Roccaluce to steal Daphne's powers, since her Sirenix was protected by the Source, the Winx and their bonded Selkies restore it and their Guardians of Sirenix activate it. Omnia, the Supreme Guardian of Sirenix, then appears and invites them to enter the Infinite Ocean, and gives them Sirenix powers.

Tritannus tried to activate the power of the Emperor's Throne but failed to and found out that it was because the leg of the Throne was broken. He then decided to steal the seals of the Pillars of the Infinite Ocean to fit them in the throne where it is broken to repair it so that he will be able to activate it. When he stole the seal of the Pillar of Light this caused an eclipse in the whole Magic Dimension that made all the realms become unstable. Even though the seal was gone, Stella managed to restore the pillar.

When Tritannus was about to place the seal of the Pillar of Light in the broken leg of the Emperor's Throne, Daphne told Darcy and Stormy to stop him, because if he succeeded he would release a power that Tritannus himself wouldn't be able to control, and would destroy the Infinite Ocean and everything and everyone, including Tritannus himself and the Trix.

When Tritannus placed the seal in the Throne, its powers attacked him and drained him of his toxic powers, making him weak enough so that his hold on Daphne became weak and she was able to contact Bloom to warn her about Tritannus' plans and tell her how to stop him.

With the seals of the Pillar of Light and of the Pillar of Balance and Aisha's Sirenix powers, Tritannus activates the Emperor's Throne and gains the ultimate power of the Infinite Ocean. However the power turns him into a monster and he attacks Icy. Tritannus is later defeated by Nereus and Bloom.

The Mystery of the Abyss
The Trix return and they try to activate the Emperor's Throne, the Trix accidentally evoke Politea, who is still cursed and is ready to ally with the Trix. She tells them that, to activate the Emperor's Throne, they need to free Tritannus from Oblivion but that they need the vital force of a king for that. The Trix kidnap Sky and free Tritannus, who becomes their ally again to get the Pearl of the Deep. Later, she meets the Winx and uses her powers against Aisha and Bloom causing them to fall to the floor of the Emperor's Throne. Then she takes away Stella's Sirenix powers which traps and tangles her in it. Later on, she pollutes Domino's ocean by using the Pearl of the Deep. She is then destroyed by the Winx never to be seen again and with her gone Domino's ocean become clear once more.

Inhabitants of the Infinite Ocean
The Infinite Ocean is inhabited by the Guardian Selkies who protect the Pillars of the Infinite Ocean, by the bollabies, the Giant Eels, the fish and the Devourers.

Trivia

 * Scenes in the Infinite Ocean will be in 3D because everything takes on another dimension there.
 * With Sirenix power, the Winx (possibly the Trix) have the ability to summon/open the ocean gate to Infinite Ocean, called "Sirenix Gate".
 * How things take another dimension in the Infinite Ocean and the Legendarium World and how 3D animation is used for this is similar to the 3D effects used in the animated series Code Lyoko, where the characters are shown in 2D when in the real world, but become 3D animated characters when they enter the world of Lyoko.
 * According to Omnia, the Infinite Ocean is forever open for the Sirenix fairies and/or Dark Sirenix witches (due to the fact that the Trix also can enter the Infinite Ocean).