The mood of Riders to the Sea is extremely bleak. Despite the fact that the play opens with no confirmed deaths—Michael is missing at sea but none of his family members know for sure that he has died—the mood is still gloomy and depressing. This comes through in Synge’s decision to have white boards present on stage from the opening scene, signaling that one (or more) characters will die and require a coffin.
As the story goes on, every conversation is marked by misery—Nora and Cathleen worry about telling their mother about the bundle of clothes that were found on a dead man in the sea (and could be Michael’s), Maurya worries about Bartley going to the sea on a stormy day, and, ultimately, they all learn that both Michael and Bartley have died and start to grieve, with townspeople joining them in the process.
The bleak mood comes across in Maurya’s lamentation near the end of the play, which she speaks after she mournfully drinks and then “puts the empty cup mouth downwards on the table, and lays her hands together on Bartley’s feet”:
They’re all together this time, and the end is come. May the Almighty God have mercy on Bartley’s soul, and on Michael’s soul, and on the souls of Sheamus and Patch, and Stephen and Shawn […] and may He have mercy on my soul, Nora, and on the soul of every one is left living in the world.
Here Maurya lists all of the men in her family who she has lost over the years, while stating “the end is come” and begging for God’s mercy on her soul and “the soul of every one is left in the living world.” The sorrowful mood is palpable as the play comes to an end.