Now how can you dispute this?
Gen 7:17 For forty days the flood kept coming on the earth, and as the waters increased they lifted the ark high above the earth.
Gen 7:18 The waters rose and increased greatly on the earth, and the ark floated on the surface of the water.
Gen 7:19 They rose greatly on the earth, and all the high mountains under the entire heavens were covered.
Gen 7:20 The waters rose and covered the mountains to a depth of more than twenty feet.
Those lines are the ONLY evidence a global flood ever happened. NONE of the physical evidence we'd see from a flood that extensive exists. Not only is there a lack of evidence FOR a global flood, but there is a MASSIVE volume of archeological, fossil, and geological evidence AGAINST it.
There IS however an explanation put fourth by Edmund Halley that correlates the Biblical account with the evidence.
First, you need to keep in mind that the Bible was clearly written from the viewpoint of the people on the surface. The Bible describes a geocentric solar system and a flat Earth with 4 corners. Either the Bible is WRONG about these facts, or it was written not as a science textbook, but as a narrative from the viewpoint of the Jews.
Now, if we look at the historical record there is AMPLE evidence of MASSIVE LOCAL floods in the fertile Crescent. The Epic of Gilgamesh is the best known example.
Edmund Halley proposed that the Biblical account was true, but it described not a
literal flood that covered the entire Earth, but a
localized, yet still devastating, flood that covered the Earth AS IT WAS KNOWN TO NOAH. It didn't wipe out all humanity, but it did clear out Noah's competitors for farmland, grazing land and other resources.
Noah still builds his boat, but suddenly instead of needing to gather koalas and giraffes,
he only needs to gather the animal life he found in the immediate vicinity. The Ark is suddenly not a comically undersized clown car of animals but a cramped yet suddenly feasible barn.
The only concession one needs to make is that the references to flooding the entire Earth were, like many other such passages in the Bible, metaphor and hyperbole, not literal.
As a bonus, this eliminates the need for Noah's descendants to be engaging in rampant incest for a few generations, as there were still other tribes around for Noah's grandchildren marry.
It is easier to believe that this flood occurred than to believe in evolution!
I used to believe the same thing. Sadly, I have a keen interest in science and, upon seeing just how slapdash and amateur men like Ken Ham were in their "science" I decided I could do better. What I found was that the Creationist literature was slap-dash in part because it was covering up a web of ignorance and lies. The more I dug, the more I realized their "science" consisted largely of taking pot-shots at Evolution and geology; most those pot-shots were based upon a misrepresentation, sometimes deliberate, of the science they were criticizing.