Discuss the significance of the title of Riders to the Sea.

In Irish folklore, supernatural horsemen and horses are recurring motifs. It's not surprising, then, that two of the apocalyptic horsemen from the Book of Revelation should appear in Maurya's vision. One of the horsemen is riding a red horse; he will take away peace. The other is riding a pale horse and is called Death. Their appearance in Maurya's vision both reflects the almost constant presence of death in this remote community as well as foreshadows its occurrence later on.
The sea of the title can taken to represent eternity. Maurya loses all her loved ones to the ocean; in that sense, her father-in-law, husband, and sons were riders to the sea. And yet the act of riding isn't often associated with the sea. This is arguably a deliberate choice of words by Synge, who wants to convey a sense of unnaturalness and doom about the ultimate fate of these men.