through-a-keyhole:

The Children of Lir

There once was a man called Lir, who was happily married with three children. The eldest a girl and the two youngest boys. He loved his family with all his heart until one day, his wife passed away. Horrified at the thought of his children living without a mother, Lir married a beautiful woman named Aoife.

Aoife was terribly jealous of her new husband’s love for his children as he adored them far more than he did her. Consumed by jealousy, she ordered one of the servants to kill the children. When he refused, she used her magic instead to turn them into swans.

The children were doomed to wander until the spell could be broken if they were blessed by a monk. To stay together, their father fashioned a gold chain to fit around all three of their necks so they would not be tossed apart on the raging waters. They spent 300 years on Lough Derravaragh, 300 years in the Sea of Moyle and 300 years in Irrus Domnann Erris.

Eventually, the swans were found by monks belonging to a monastery on an island. They blessed the swans and they changed back into humans, but being 900 years old, they were withered and ancient. They three were buried together, the gold chain still linking their necks.