As it turns out, this theme is particularly relevant for "Sea Rose" – see, the poem is all about nature. After all, it's an Imagistic poem about a rose. So we get to hear all about the rose – how it looks, where it lives, and how it survives in the midst of a not-so-welcoming climate. But here's the kicker: the rose could also be a metaphor for a person (like, say, the poet) who lives outside of the world's norms.
Although this poem is overtly describing a rose, it also speaks to the troubles of a woman caught in restrictive social codes.
Though readers may be tempted to read this poem as an extended metaphor for all sorts of troubles, such readings obscure the actual subject here: a rose.