This link to the Mythology Guide gives a thorough and poignant account of Ceyx and Halcyone.
Birds of a Feather
Higgledy-Piggledy
Ceyx left Halcyone,
Sailed for Ionia,
Drowned in the sea;
Pitying gods, in their
Misericordia,
Changed them to kingfishers,
Answered her plea.