God saw wickedness in the world and that the all human hearts had become evil. Other Gods were being worshipped, humans werent truthful yet were sinful.
As God continued to watch his sons and daughters act this harmful way to their Father, He regretted making the human race. So He made a decision to wipe all human kind off the earth along with animals.
To accomplish God's wishes he trusted a righteous, blameless man during the time to build an ark, and whoever entered may be saved from the flood that has yet to come.
Noah set off and did as what he was told, and built an ark made out of gopher wood with the dimensions of being three hundred cubits long, fifty cubits wide and thirty cubits high.
Noah finally went out and collected all the animals per God's request
The flood started and went on for fourty day and fourty nights and Noah stayed on the ark continuing to follow as God commanded.