This is the first major image we come across in the poem. Poe uses it a bunch of times, always as a part of the phrase "a kingdom by the sea." In poetry we call that repeated phrase a refrain. You can think of it like a chorus in a song. The verses tell a story, but the chorus comes back to the main images again and again. Rhythm is a big part of poetry, and this refrain helps give this poem its rhythm.
- Line 2: We see the phrase "a kingdom by the sea" over and over. Thinking about what this phrase means will help to set the tone for the entire poem. We think it gives the whole thing a kind of fairytale feel. When it comes to Poe's writing, we can't always be sure exactly where we are. He uses this word four more times in the poem, but we never get any specifics about the kingdom. A lot is left to our imagination. It seems like it's there to give us an intense image of a time and place a long way from our own.
- Line 20: In this line the wording is the same as in line 2, but now the word kingdom comes right after the story about the "highborn kinsman." So now the kingdom might call up images of powerful, rich people who can just take things without asking. In that case, the kingdom becomes a symbol of tyranny and cruelty. It's part of what makes the world such a bad place to live for our poor speaker.