Dark Island

"Mercy! Mercy! Even if you are only one more dream, have mercy. Take me on board. Take me, even if you strike me dead. But in the name of all mercies do not fade away and leave me in this horrible land"

- Rhoop

The Dark Island was a highly mysterious area located in the Eastern Ocean where any approachers spontaneously began to experience frightening hallucinations. It was basically a region of semi-solid fog-like darkness, with no obvious shore or land mass. Caspian X and his crew attempted to pass through this "island" on their voyage in the Dawn Treader. Lord Rhoop was trapped on this island for a time, and when rescued said that it was the Island where Dreams Come True. (But not in a good sense--here it means that you relive nightmares.) He requested never to be asked what he saw during his stay. Then the Dawn Treader sailed away with the island fading away into the distance. Once you're on the island, the only way to leave is with Aslan's help.

Differences between versions
In the British version and now all recent publications have the Lord Rhoop asking Caspian never to take him back to that island, and when the Dawn Treader leaves it they look back to find the island gone, destroyed by Aslan. In the American version, the Island is not destroyed.