According to Genesis, the Ark’s entry was a door in its side.
Genesis 6:16 describes the vessel’s design and says that Noah was to set its door in the side. The same passage also mentions a roof or opening above and three decks, but it does not describe multiple entry doors.
The door is significant in the narrative because Genesis later says that Noah entered the Ark with his family and that the LORD shut him in. The text therefore presents the door as both a practical entrance and an important narrative detail.
Readers sometimes call the opening a gate or hatch because modern boats use several kinds of entrances. Those terms are not the wording of the Genesis account. The text specifically identifies the entry as a door and locates it in the Ark’s side.