What is a cubit? What kept a boat that size from falling apart from storm swells? How did it stay afloat?
Where did Noah and his family and his animals land? Where are the "mountains of Ararat?" Is the ark still in the same place after 5000 years?
What brought on the flood? How deep was it really? Where did all that water come from?
Can it happen again?
There are lots and lots of theories. Hard evidence is almost totally lacking.
If we can believe it was "an act of God," it's not much of a stretch to think of the flood as a natural event -- i.e., caused by something beyond the control of man, perhaps beyond even the imagination of man.
The ancients developed quite a knowledge of astronomy, yet had an irrational fear of comets that carried into relatively modern times.
Or was their fear rational?
I've heard that Haile-Bopp was seen just before the Flood.
I don't think fear of comets was anything irrational. I think it was grounded in experience. See The Cosmic Serpent. As far as where all the water came from: there are still several times more water trapped in the crust than in the oceans and seas at present. As far as what is a cubit, etc., Fasold explores that and other questions you raised.