"Dream-Land" tells the story of a journey, although it's never quite clear where that trip starts or where it ends. For the most part, the poem describes the strange and amazing sights the speaker sees along the way.
We begin with a tantalizingly vague description of the speaker arriving in a strange new land. He doesn't say where exactly he's coming from, just that it was far away, beyond the borders of space and time. The place he's arrived in is haunted by evil spirits and ruled by the creepy, dark figure of "Night." This new country has a huge landscape of oceans, valleys, caves, and forests. Nothing looks or moves the way it does in everyday life. Mountains tumble, the sky is on fire, the ocean leaps up, the snow sits on the ground forever. Sometimes this world is violent and exciting, sometimes it's creepily quiet and still, but there's a sad loneliness everywhere.
It's not just the landscape that's strange and sad. Apparently the speaker sees ghosts on his journey too, the spirits of dead loved ones. Weirdly enough, this makes the speaker feel kind of good. Apparently his life has been tough, and he prefers to live in this strange and different land. He only gets a glimpse of the mysterious world when he is sleeping, but he still loves it and treasures those moments.