Preparation for the Flood & The Great Flood Gn 7
God tells Noah that He is going to create a huge flood that will destroy all of mankind due to sin spreading. He tells Noah this because He noticed that him and his family were righteous to God so, God wanted to save them.
"Go into the ark, you and all your household, for you alone in this generation have I found to be righteous before me. Of every clean animal, take with you seven pairs, a male and its mate; and of the unclean animals, one pair, a male and its mate; likewise, of every bird of the air, seven pairs, a male and a female, to keep their progeny alive over all the earth. For seven days from now I will bring rain down on the earth forty days and forty nights, and so I will wipe out from the face of the earth every being that I have made" (Gn 7:1-4).
"Together with his sons, his wife, and his sons' wives, Noah went into the ark because of the waters of the flood. Of the lean animals and the unclean, of the birds, and of everything that crawls on the ground, two by two, male and female came to him" (Gn 7:7-9).
"The flood continued upon the earth for forty days. As the waters increased, they lifted in the ark, so that it rose above the earth... all creatures that moved on earth perished... the Lord wiped out every being on earth. Only Noah and those with him in the ark were left" (Gn 7:17, 21, 23).
If you believe and obey God, anything is possible.