According to Genesis, Noah’s Ark had one door.
Genesis 6:16 instructs Noah to make a door in the side of the Ark. The verse describes the vessel’s opening in the singular, alongside its roof and three decks. Thus, the canonical answer is one door, even though artistic reconstructions may show additional hatches, windows, or access points.
The door is not the same feature as the window mentioned later in Genesis 8. Noah opens the Ark’s window to send out a raven and doves after the waters begin to recede. Genesis therefore distinguishes the principal entrance from the opening used for observing conditions outside.
The text does not provide a detailed engineering account of hinges, locks, or the door’s exact dimensions. Its singular wording is the reliable fact. Questions about replicas or modern reconstructions can have different answers, but they do not change the number stated in Genesis.