From the introduction: Each room is a 30 foot x 30 foot by 30 foot cube. There is a 10 foot x 10 foot square hatch centered on each of the six sides of each cube, along with four buttons centered along each edge of the hatch. Pushing any of these buttons opens the hatch; a second push (from either side) closes the hatch. ... This makes a good adventure for a new adventuring party to meet each other, when they all awaken in the tesseract with no memories of how they got there.