Genesis 6:15-16

This is the way you are to make it: the length of the ark shall be three hundred cubits, its width fifty cubits, and its height thirty cubits (450’ x 75’ x 45’). You shall make a window [for light and ventilation] for the ark, and finish it to at least a cubit (eighteen inches) from the top—and set the [entry] door of the ark in its side; and you shall make it with lower, second and third decks.