Noah's Ark, partially tall tale and partially true history. The probelm is there was a flood in the area that was much larger than what the locals thought was the extent of the world. So over time it became the whole world being flooded. Rather simple. Still doesn't negate the story of Noah. Godd could have easily told him what was needed to save the local ecology and civilization and he did. Over the years and different tellings it has become twisted a little, like all history does.
