During the film’s ending, Tia Dalma tells Jack Sparrow that he cannot set foot on land until he has found his true love. This is a reference to Calypso, the sea goddess who imprisoned Odysseus for seven years, only to find that he was only ever pining for home.
In the original myth, Calypso was a beautiful nymph who fell in love with Odysseus and wanted to make him her immortal husband. But he only wanted to return to Ithaca and refused her gifts of eternal youth and beauty. She even turned her suitors into animals, but Odysseus always remembered his main intention and was still determined to save her.
When Odysseus finally broke free, Calypso was furious. She cursed him to spend his life searching for his loved one and to die if he ever saw them again. This was a terrible fate, but it was the only way she could keep him from falling in love with another immortal.
Later, when she was released from her human form by Davy Jones’ betrayal, Calypso screamed an incantation that roughly translated to “Across all the seas, find the path to He who wrongfully entombed me!” Before dissolving into a swarm of crabs, she also shouted the name of Jack Sparrow. This shows that she never forgot about her love for him.