The Isle of Dreams is an island somewhere in one of the nine seas. As a young boy Dare Larsett mentioned it as one of the things he wanted to find.
Shadows of the Master
As a young boy Dare Larsett wanted to sail the nine seas and find all of the wonders he had read about in tales, including the Isle of Dreams. He asked the Trader Rosalyn at the time, Mab, if he could come and work as a trader so that he could find the wonders, but Mab told him that his wish made him a treasure hunter as opposed to a trader and that it would do him no good to seek them.