The motif of water in The Rime of the Ancient Mariner is a multifaceted element that symbolizes life, death, isolation, and the unpredictable forces of nature. The opening lines set the stage for the significance of water, as they describe the Mariner's journey "driven by Storms to the cold Country" and how his ship "made her course to the tropical Latitude of the Great Pacific Ocean." This vast expanse of water represents the isolation and desolation that the mariner experiences, emphasizing the profound loneliness resulting from his impulsive act of killing the albatross.
Later in the poem, the sailors aboard the ship find themselves surrounded by an endless sea but are unable to drink the salty water. The paradoxical situation of "Water, water, every where, [...] Ne any drop to drink" not only highlights the physical hardship of the sailors but also serves as a metaphor for the inability to find spiritual sustenance in their dire circumstances. Likewise, water is instrumental in the Mariner's journey toward redemption. The appearance of water-snakes, which initially seems menacing, ultimately becomes a source of blessing and salvation for the mariner. In Part IV, he says:
Beyond the shadow of the ship
I watch'd the water-snakes:
They mov'd in tracks of shining white;
And when they rear'd, the elfish light
Fell off in hoary flakes.
Seeing the snakes is a crucial moment of spiritual transformation that marks beginning of his repentance and the lifting of the curse. The "tracks of shining white" and "elfish light" make the snakes seem supernatural and otherworldly. The speaker seems to be having a quasi-religious vision that brings him to realize the beauty of nature. This, in turn, causes him to reflect on his actions and repent for killing the albatross, who was just as much a part of nature as these beautiful water-snakes. The "tracks" that the snakes make in the sea mimic the foamy white waves of the ocean and suggest the unity of nature. Throughout the poem, water helps develop the poem's central themes: it appears as a life-giving force, a source of profound suffering, and a redemptive inspiration.