In a dream, a little boy sails alone in a small boat across an enormous sea. He pictures himself as a brave sailor, resting after a pirate fight, but the adventure soon turns lonely: he is far from home and play, with only the sea and fish for company, and even the fish swim away. The repeated phrases and rocking rhythm make the poem feel like a lullaby or the sway of a boat.
The final lines pull the dream back to reality. The boy cries out for his mother and wakes to find he was never really alone—he is in a rocking chair with her arms wrapped tightly around him. The mood shifts from exciting but slightly frightening independence to warmth and safety.