The wrath of Calypso
Over the years, the imprisoned Calypso assumed the alias of a voodoo mystic named Tia Dalma. She began living out of a shack on the Pantano River. She kept with her a locket that matched one carried by Davy Jones, and would play a mournful tune that hinted at their lost love. Dalma befriended Jack Sparrow during his early life; the man who would go on to become the Pirate Lord of the Caribbean Sea, and thus integral to Calypsos desire to escape her human form.
With the death of Hector Barbossa, the Pirate Lord of the Caspian Sea, came a prime opportunity. Tia Dalma/Calypso needed all the Pirate Lords in order to assemble the Brethren Court, so they could release her from her human bonds. And so, through undetermined circumstances, she resurrected Barbossa from the dead and tricked him to summon a meeting of the Brethren and retrieve Jack Sparrow, who was taken to Davy Jones Locker by the Kraken. Barbossa set off on a mission to free him, and therefore ensured that Jacks Piece of Eight was not lost.
On the quest for freeing Jack Sparrow from the Locker, the crew led by Barbossa captained the Hai Peng into Worlds End. They landed in the Locker, where Jack Sparrow noticed that the Pearl was being dragged across the sand by crabs. The ship reached the crew with the help of the crabs that were actually under the control of Calypso. After escaping the Locker, the Black Pearl went on its way to meet with the Brethren Court.
By the time the Black Pearl reached the coast of Shipwreck Island, Barbossa stood on the ships forecastle, conversing with Tia Dalma, regarding their bargain. The mystic accused him on intending to betray her and therefore reminded him on that he was brought back from the dead by her power, and also, demonstrating her abilities by briefly decomposing Barbossas right hand, cautioning him of his fate should he fail to keep his end of the bargain. Barbossa in turn reminded her that she, secretly the goddess Calypso, was the one who needed him; she resurrected Barbossa so he could help retrieve Jack Sparrow from Davy Jones Locker and summon a meeting of the Brethren Court, since only the nine Pirate Lords had the power to free Calypso. To avoid the risk of the goddess reaching an accord with someone else, Barbossa ordered Pintel and Ragetti to lock Tia Dalma in the brig. Barbossa remained on deck, glancing at his right hand while contemplating his debt.
By this time, the machinations of Lord Cutler Beckett had forced the Brethren Court to convene for the fourth time in its existence, and it was here that Barbossa brought up the notion of releasing Calypso. During the meeting, Ragetti absconded with all but two of the Pirate Lords Pieces of Eight—the eighth was collected by Barbossa himself from Elizabeth Swann and the ninth from Jack Sparrow. All nine were gathered aboard the Black Pearl, where Tia Dalma had been bound. Ragetti completed the incantation that would release Calypso, and the pieces of eight set alight. Moments before she was released, Calypso finally learned who had called upon the Brethren Court to capture her all those years ago: Will Turner informed her of Davy Jones betrayal.
Enraged, Calypso, still in Dalmas form, grew massive in size, dwarfing the crew of the Pearl. After being freed from her human bonds, Calypso yelled in her native tongue, seemingly as insults to the pirates but in reality it was an incantation, before exploding outwards in a shower of crabs. Calypsos spirit, now free at last, disappeared into the air, though her influence on events was not ended. As the Black Pearl and the Flying Dutchman prepared for a showdown, Calypso used all of the power of the seas to unleash a terrible storm, which created a maelstrom between the two fleets. And the wind from the storm evened the balance for the Pearl and caused Davy Jones to let out a cry of anguish as he realized what the storm signified.
The battle that followed sealed Davy Jones fate, as Jack Sparrow helped Will Turner stab Jones disembodied heart. With his last breath, Jones whispered Calypsos name, and toppled into the maelstrom, which soon abated when the Flying Dutchman itself followed its former captain. Whether Calypso and her love were reunited after Jones death remained unknown.
In ancient mythology and lore, Calypso was described as a heathen goddess, though it was also said she had mortal blood. Daughter of Atlas, she was described as a woman as changing, harsh, and untamable as the sea. As a heathen goddess, Calypso was able to take many forms. But since the crab was attributed as her symbol, most notably by pirates, she chose that form. Of Calypsos beauty and power, all sailors were in awe. Her womanliness was unsurpassed in grace and bearing. She was as changeable and whimsical as the sea itself, and exemplified the deepest charity and brilliance of womans mercurial nature. Calypsos powers were only eclipsed by the great god of the sea Poseidon himself, and only Zeus, chief amongst all gods, could command her.
As with all beings of great might, she was both a nurturer and a destroyer. Calypso had dominion over all the seas, and all sailors everywhere both loved and feared her. Nevertheless, she was the protector of all sailors. It was she who sent forth the Flying Dutchman to rescue souls lost at sea. Calypso also designed a special metal chamber in which the mermaids locked the magical gems of Poseidon, thus making themselves immune to the power of the Trident of Poseidon.
Jacks crew would soon return to Tia Dalmas shack, but this time without their Captain. Jack had fallen to the Kraken, going down with his ship as the beast dragged the Black Pearl down to Davy Jones Locker. Tia had apparently foreseen this eventuality, and informed the mourning crew that there was a chance to save Jack. Their journey would take them to Worlds End, but, though Tia would be joining them on their quest, they would need the leadership of a Captain who knew the waters of Worlds End. With that, she introduced the resurrected Barbossa to the stunned crew.
It appeared that Tia had been responsible, either partly or perhaps completely, for Barbossas return to the world of the living after Jack shot him in the heart on Isla de Muerta a year earlier. Tia, seemingly more powerful than any of the crew could have guessed, seemed set to lend her mystical aid to the return of Captain Jack Sparrow at Worlds End.
Tia Dalma sailed with the rest of the crew to Singapore and took part in the fight against Lord Cutler Becketts men. She went with the group as they sailed to Davy Jones Locker. Her power let her command the crabs there to drag the Black Pearl back to the sea.