The mermaids that Prufrock imagines are a wonderful example of symbolism. When Prufrock imagines his solitary old age, he pictures himself walking upon the beach:
I shall wear white flannel trousers, and walk upon
I have heard the mermaids singing, each to each.
I do not think that they will sing to me.
The mermaids represent the sirens of romance. While Prufrock thinks that he will always feel a longing for love, he does not believe that it will be reciprocated. He casts himself as an ordinary human in comparison to the mythological creatures who find love, furthering his distance from it.
Alienation is a major theme throughout the poem. Prufrock wanders aimlessly along the narrow streets at odd hours in lieu of seeking company and companionship, and finds himself lonely and awkward at the parties he attends; he wishes for a companion but absorbs himself in his own world. In fact, the scene in which Prufrock imagines the mermaids occurs is, presumably, the same party in which the women “come and go;” it is the voices of other guests that wake him from his fantasy:
We have lingered in the chambers of the sea
By sea-girls wreathed with seaweed red and brown
Till human voices wake us, and we drown.
His notions of romance, distant as they may be, are quashed by the people around him. While Prufrock dreams of a woman, he finds the ones at the party shallow, with their unrelenting talk of Michelangelo and gossip. His dreams and reality do not align, and unfortunately, his dreams must give way.
A symbol in the poem is the mermaid. Mermaids are like fantasy, unreachable, unattainable and impossible to have them. Prufrock uses this image to say that happy ending ( what he wants to do: marriage for instance ) is so far way that he can never be able to reach it. therefore describe his feeling of being hopeless and disappointed.