One-act play of John Millington Synge (1871Synge ( -1909 Riders to the Sea (1904) is about the life in the Aran Islands, power of nature and death. While the life endowed with the sea determines the fate of Irish islanders, their dependence on the water surrounding the Aran Islands brings death, too. The sea both provides life and causes death in the play. However, agency of the sea is not just bound to this dualistic nature in Synge's work. The vision of the mother Maurya about the deaths of her two sons, Michael and Bartley, upon the sea evidences that agentic power of the water is not only affiliated with its ontological presence, but also its epistemological capacity which is about the narrative ability of matter. This paper sets out to scrutinise agency of the sea in Synge's Riders to the Sea in terms of material ecocriticism and new materialisms.