But it's WRITTEN!

If you accept the Bible's chronology the Flood happened between 2500 and 2300 BC.

The Egyptians, a civilization which features prominently in the Bible and were certainly local enough that a flood which covered Mount Ararat would have covered them even if it weren't truly a worldwide flood, have continuous written records stretching back to 2925 BC.

Those records include extensively detailed tax rolls, listing things like harvest amounts, populations of villages, trade agreements with neighboring states and so on. What they don't include is a description of the year the entire kingdom was under water. They contain no mention of any flooding even remotely of that magnitude, only of normal, localized floods along the Nile.

The Sumerians and the proto-Elamites, similarly, have written records covering the entire period. Those of the Sumerians are similarly detailed concerning harvests and so forth, and again make no mention of any such deluge affecting them. We can't read those of the proto-Elamites, sadly, but they can be dated and they also show no indication of any universal calamity in the timeframe of the supposed flood.

Since there is no physical evidence whatsoever of such a remarkable flooding, and at least two major local civilizations failed to record it, the simplest explanation is that it never occurred.

Incidentally, the records of the Egyptians also make no note of the series of plagues which the God of the Hebrews supposedly visited upon them in the following book of the Bible - not even the deaths of the firstborn, which would have affected any number of inheritances, including that of the Pharoah's throne. Similarly, in the New Testament the Slaughter of the Innocents left no traces in the records of King Herod's tax collectors, and went unrecorded by any of the neighboring literate states, even the notably bureaucratic Romans.

This to say the least should cast doubt upon the historical reliability of the ancient Hebrew scribes.