The Great Flood was a global cataclysm that covered the whole world, killing all air breathing land animals and birds except within the ark which Noah had built based on a pattern given him by God Himself. The flood was the Creator's action in response to the level of violence and disinterest that the population of the world had risen
The World That Was Edit
In six days - each having an evening and a morning in that order -- the LORD God created everything that exists. The earth had been deemed "very good" by God himself. Everything worked properly, the animals co-existed while eating plants created specifically to be food.
In the highlands was the place of the Garden of Eden, from which flowed a great river that split into four lesser rivers that provided water for the rest of the world. The world was a large field, sown with all manner of plant life, but hydrated naturally by a mist rather than rain. Eden, at the center of the great continent, was especially prepared as a home for mankind, with the plan to spread to every part of the world.
After leaving Eden, Adam and Eve found a world less friendly to cultivation. The dew and ground water was not enough to sustain the widely dispersed food sources that mankind needed. This required men and women to work much harder -- to work up a sweat -- to get anything near what they had in the Garden. But the command to multiply and fill the earth with people became even more important. Large families were a must in order to coax food from the ground.
The original perfection of both mankind and the world around them lent well to the success of man apart from the direct protection that was theirs in Eden. Having turned from God, mankind proved resourceful. There is no doubt that the civilization that is evident immediately after the Flood was based on knowledge acquired before it.
Though people worshiped the true God, the Creator in the early years, the descendants of Cain, with possible collaboration from fallen angels, became more and more selfish, living each day for themselves. This led to constant in-fighting and violence of the sort of Cain their father. The descendants of Seth could not escape the corruption of their neighbors. In the end, the LORD found Noah worthy of notice, choosing to show mercy upon him. With one hundred years to work, Noah would build an ark to preserve life as it would be known after the flood.