One day she took them to drive in her chariot. Reaching a lake, she told them that they might bathe in the clear water; but so soon as they were in it she struck them with a fairy wand and she turned them into four beautiful snow-white swans.

Then Finola asked, “How long shall we be in the shape of swans?”.

“For three hundred years,” said the woman, “on smooth Lake Darvra; then three hundred years on the sea of Moyle”; “and then three hundred years at Inis Glora, in the Great Western Sea”.

She left them, and before long their father, King Lir, came to the shore and heard their singing. He asked how they came to have human voices. “We are your four children,” said Finola, “changed into swans by our stepmother’s jealousy.”

(...)

But the time came when the nine hundred years of banishment were ended, and they might fly back to their father’s old home, Finnahà, but everything was changed by time—even the walls of their father’s palace were crumbled and rain-washed.

One May morning, as the children of Lir floated in the air around the island of Inis Glora, they heard a faint bell sounding across the eastern sea. 

When they touched the shore, the weight of all those centuries fell upon them; they resumed their human bodies, but they appeared old and pale and wrinkled, and they died.