The legend of St Dwynwen goes like this...
She was the prettiest daughter of 5th-century Welsh king Brychan Brycheiniog. She fell in love with a prince called Maelon Dafodrill, but her father was determined she would marry another man.
Dwynwen was devastated and begged god to make her forget Maelon. An angel visited her, with a potion to erase all memory of him, and turn him into a block of ice.
God then gave her three wishes. She wished that Maelon could be thawed. She wished that god could meet the hopes and dreams of true lovers, and that she would never marry.
She devoted herself to religion, and founded a convent on the island of Llanddwyn, off Anglesey.
According to legend, Dwynwen's well on the island contains a sacred fish. It's said that the fish can predict the happiness of relationships. Many visitors go, hoping that, if the water boils, love and good luck will follow them.