Noah's Ark was a vessel built by Noah and his sons under the direction of God during a period of time before the worldwide flood came. The purpose of the boat was to hold two of every unclean animal, one male and one female, and to hold Noah and his family (his wife, his three sons, and their wives). Also it would hold 7 pairs of clean animals --- more of the clean animals so that Noah would have something to sacrifice. This boat would protect all passengers aboard the massive vessel from the worldwide flood, and in time would recreate all populations after it.
Genesis, Chapters 6 - 9