Translations:The Legend of Zelda: The Wind Waker/Unused Rooms/Page One/57/en

The extra door is located on the opposite wall from a door in Room7, which is the long wind tunnel room filled with Wizrobes. When Room7 and the unused Room6 are compared against the location of the door, as seen in this picture, it is revealed that it would have connected the two chambers. Moreover, a spawn point for Link is still present in the final version, although it's been lowered into the ground.