According to Genesis, Noah's Ark had three decks.
Genesis 6:16 describes the ark as having lower, second, and third decks. The instruction appears in the construction passage, alongside directions to make a window and an opening in the side. The three-level design is therefore a textual detail, not a measurement inferred from later artwork.
The ark's stated dimensions are 300 cubits long, 50 cubits wide, and 30 cubits high. Dividing its height into three decks gives the vessel a broad, box-like profile. Artists and filmmakers often portray it with additional visible floors, but those details are imaginative rather than specified by Genesis.
The three decks are also distinct from the ark's overall compartments. Genesis says Noah was to make rooms in the ark, but it does not provide a detailed floor plan or identify where particular animals were kept. Later traditions and reconstructions add such features, while the biblical account gives only the basic three-deck description.