Science has identified many floods throughout the geological record.
Any of those, if recorded on YouTube, would be accepted by believers and non-believers alike.
But science has never found evidence of a single Great Flood which covered the entire earth up to the level of Mount Ararat (Genesis 8:3-5) -- around 17,000 feet -- and then receded to current levels.
Where scientifically, could such volumes of water have come from, or gone to?
Even the great asteroid strike in the ocean near Chicxulib, Mexico, left no evidence of walls-of-water floods so high.
Fortunately, specific depths of flood waters are not important, even to verify the point of Noah's story, which is G*d's promise never to do it again.
G*d promises that despite our sinfulness, while He may punish us for it, He will not destroy everything by flood.
Some will survive, the world will go on...
Seems to me that's good to know, regardless of how high certain floodwaters may, or may not, have reached. :-)
It’s also curious that the oldest civilization in the Middle East — Egypt — has no flood story at all, despite the fact that the 4th dynasty’s Great Pyramid at Giza was built three hundred years before the literalist estimate for the date of the Noachian flood. The closest we get to an Egyptian flood story is the tale of Atlantis which Plato, writing as Socrates, claims came from Egypt via Solon.