What is the major theme of the poem 'Not Waving but Drowning ' by Stevie Smith?

This is a poem about the failures of communication. Although the poem begins with a lighthearted tone, the final stanza confirms what the poem is really about. It is revealed that the old man has struggled for much of his life, presumably with his mental health. However, it is insinuated that his cries for help were never properly understood. Here, his drowning and the subsequent miscommunications are used as a metaphor for his inability to seek help for his struggles his whole life.

For additional information about the poem's themes, check out GradeSaver's theme page in its Study Guide for the unit.