Genesis 6:15-17

15 And this is how you must make it: The length of the ark will be three hundred cubits, the width of it fifty cubits, and the height of it thirty cubits.

16 Make an opening one cubit below the top of the ark all around; and you must set the door of the ark on the side. Make it with a lower, a second, and a third story.

17 I will bring a flood of waters on the earth to destroy all flesh, wherever there is the breath of life under heaven, and everything that is on the earth will die.