There is more than one story about The Dolphin from the Sea (Duful de Mare).
The first three of them are sung as ritual Christmas songs.
On the seashore there grows a tall tree with golden bark and golden apples, whose branches are almost reaching to the sky. But, as soon as the fruits ripen, they are eaten by the Sea Dolphin; Dulful de Mare, which invades and disturbs terrestrial territory. The apple cries out for help. It is heard by a brave young man, who takes his bow and arrows and lurks for the Dolphin to come out from the sea. But as the lad is about to throw the arrow, the Dolphin speaks: "It's no use trying to kill me! We are nine brothers, all of whom have been shot, but none of us died, for we hide in the sea". The hero renounces to fight with the Dolphin, which retreats back under the sea.
Its similar to the previous one, but ends differently: the brave young man has a sister who accepts to marry the Dolphin if he promises that he will never attack the golden apple again.
(Realms of land and of water are restored, hence the balance of the world is assured for one more year, until the next Christmas. The apple tree is a vertical axis of the world, which confers stability)
(when speaking about marriage, the song is performed on behalf of young members of the traditional community, who are expected to marry that year)