From the very beginning of "Dream-Land," we can tell we're not in Kansas anymore. Even the title lets us know that we're entering a different world. Dreams are definitely involved here, and we see all kinds of impossible, unreal sights. Still, Poe doesn't make it so easy to figure out what's going on. He doesn't let us off the hook by saying: "And it was all a dream!" at the end. Instead, we're on a weird, scary trip into another dimension, and we can't really tell where we started from or when we might be going back.
The poem presents a variety of different possible realities and imaginary places, including Eldorado, Dream-Land, and Ultima Thule. This confusion forces us to reconsider the line between dream and reality.
Despite the wonder and excitement of the journey, there is a deep pessimism in this poem, since all escapes, all fantasies, eventually fade away into nothingness.