Book Appearances: The Voyage of the Dawn Treader and the wider series
Movie Appearances: The Chronicles of Narnia: The Voyage of the Dawn Treader
Overview: The Great Eastern Ocean is the sea stretching east from Narnia toward the islands, the utter east, and the edge of Aslan’s world.
Place in the books
The Great Eastern Ocean matters because it turns the east into more than a direction. It becomes a spiritual and imaginative movement. The farther east the voyage goes, the more beauty, danger, and revelation begin to converge.
It also helps tie multiple islands into one coherent frontier. Without the Ocean, those places would feel disconnected. With it, they feel like stages in one great eastward calling.