In Genesis, the Ark had three floors or decks.
Genesis 6:16 instructs Noah to make the Ark with lower, second, and third levels. The verse also mentions a window or opening and a door in the side, giving a compact description of the vessel’s layout.
The three-level design is part of the Ark’s stated specifications, alongside its length, width, height, and waterproof coating. Genesis does not provide a detailed floor plan, explain how animals were assigned to levels, or identify the dimensions of each deck.
Illustrations often add ramps, stalls, cages, and elaborate rooms, but those features are artistic reconstructions rather than details supplied by the biblical text. The safest canonical answer is therefore the number explicitly given: three.