The Nephilim were on the earth in those days (and also after this) when the sons of God were having sexual relations with the daughters of humankind, who gave birth to their children. They were the mighty heroes of old, the famous men.
But the LORD saw that the wickedness of humankind had become great on the earth. Every inclination of the thoughts of their minds was only evil all the time.
So the LORD said, "I will wipe humankind, whom I have created, from the face of the earth— everything from humankind to animals, including creatures that move on the ground and birds of the air, for I regret that I have made them."
So God said to Noah, "I have decided that all living creatures must die, for the earth is filled with violence because of them. Now I am about to destroy them and the earth.
I am about to bring floodwaters on the earth to destroy from under the sky all the living creatures that have the breath of life in them. Everything that is on the earth will die,
Of the birds after their kinds, and of the cattle after their kinds, and of every creeping thing of the ground after its kind, two of every kind will come to you so you can keep them alive.