The theme of mortality is present throughout Riders to the Sea, as evidenced by both the death of Bartley and the death of Michael. Death is always on the minds of the characters within the play. From the very beginning, Cathleen and Nora discuss the bundle of clothing that represents all that is left of their brother Michael, and the two girls even resort to hiding the evidence from their mother in order to protect her fragile mental state. Their attempts are not met with success, as Maurya realizes that conditions at sea are awful and recognizes the clothes as belonging to Michael. When Bartley leaves, Maurya becomes convinced that he, too, will now die, and in this she is proven correct. In the play’s final lines, Maurya expresses her acceptance of morality by stating that

No man at all can be living for ever, and we must be satisfied.

It seems the men that exist within this play’s world are all fated to die at the hands of the sea. The men are forced to make a living from the sea, yet it appears that their work ensures certain death at some point. To illustrate this, all of the men in Maurya’s have died from a life on the sea. This is the reason why she tries to convince Bartley not to go to sea in the first place. The eventual fated death of Bartley is hinted at so much in the text that, when Bartley’s death eventually comes, it isn’t particularly shocking to readers or audience members. We have heard characters talk about it, and we have even seen it symbolically shown to us through the white coffin boards and the rope that Bartley makes into a noose-like halter. Maurya’s words after Bartley’s departure are an overt indication of the theme of fate and humanity’s powerlessness against it:

He’s gone now, God spare us, and we’ll not see him again.

Having already lost all her other sons to the sea, Maurya accepts what she believes to be Bartley’s inescapable fate.

Nature’s power is thematically important throughout the play in that the sea isn’t a neutral entity. The men are forced to make a living by working on the sea, yet everybody seems to know that the sea is going to eventually take any person’s life who earns their living in this way. The storm also indicates to readers that nature’s power is to be respected. Maurya assumes that Bartley won’t go to sea because the storm is too powerful for the men to venture out that day. Tragically, Bartley does go to sea, is thrown into the waves, and is killed. Maurya seems to come to a kind of truce with the sea in the end; it has now taken all the men in her life from her, and thus its power over her is neutralized. She reflects,

They’re all gone now, and there isn’t anything more the sea can do to me.