The flood is parable, not literal.
The "firmament" separates the "waters above" and the "waters below".
Revelation 17:15 tells you the "waters", WHERE THE WOMAN SITS, stands for people and nations.
Noah got drunk on wine and fell asleep, his son "saw his nakedness" and told his brothers. His brothers "walked backwards" and covered Noahs nakedness with a "blanket".
"The understanding of this message will bring sheer terror. Indeed, the bed is too short to stretch out on, and the blanket too small to wrap around you." - Isaiah 28:19-20
There's a very important part of the bible MANY are missing…
"And he said unto them, He that hath ears to hear, let him hear. And when he was alone, they that were about him with the twelve asked of him the parable. And he said unto them, Unto you it is given to know the mystery of the kingdom of God: but unto them that are without, ALL THESE THINGS ARE DONE IN PARABLES: That seeing they may see, and not perceive; and hearing they may hear, and not understand; lest at any time they should be converted, and their sins should be forgiven them." Mark 4:9-12