The speaker feels trapped by life away from the coast. She sees people choose plots of land and build houses far from the ocean, far from the sound of water sucking at ledges and waves striking the shore. She cannot understand what they long for, because her own longing is so physical: she aches for one salt smell of the sea once more.
That ache turns desperate in the second half. She imagines people who have never been jolted awake by waves slapping boats in a harbor. But in her own inland bed, she starts up feeling the walls close in, with no window or door, and cries out to God for death by drowning. The poem creates a mood of claustrophobia and almost violent nostalgia—the sea becomes memory, freedom, and a kind of relief that dry land cannot offer.