Genesis describes Noah’s Ark as having three decks. The construction instructions in Genesis 6:16 mention a lower, second, and third deck inside the vessel.
The same verse also refers to a window or opening and a door in the side of the ark. These details are part of the biblical description, which presents the ark as a large enclosed structure divided into compartments. The account does not provide a modern engineering blueprint or explain how every space was arranged.
The three-deck detail is sometimes overlooked because retellings concentrate on the animals, the flood, or the rainbow. It is nevertheless one of the explicit architectural features in Genesis. The decks would have increased usable interior space within the long rectangular vessel described by the text.
The number should not be confused with the ark’s three principal external dimensions: 300 cubits long, 50 cubits wide, and 30 cubits high. Those measurements describe size, while the answer here identifies the number of internal levels.