For the people that the Lord has chosen to believe in Him and in the redemptive work of Christ for their salvation, a trusting faith that all of His Word is true, including the Genesis flood, is no big stretch. For those who the Lord has chosen would not come to a believing, saving faith, you could show them a YouTube of the flood and they still wouldn’t believe.
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. :-)