I realize that this topic has been addressed here and there in many threads. I'd like to collect all the points into one clearly labeled thread. Let's list all the arguments and evidence against the flood. They can include, for example, geological evidence, or internal problems with the Genesis account.
I'll start.
If there had been a global flood, there would be a single layer of silt extending all around the world. No such layer of silt exists.
Regarding history, there is a story written in Mesopotamian and biblical myths of the flood that happened. You can read the info here:
Noah | Biblical Hero, Flood Survivor & Patriarch
To me, I wondered if there was an earlier event that could have been changed into what was eventually written, and, it seems there were two. in and around 6000 BC the side of Mt Etna slid into the Mediterranean and caused a mega tsunami. (The video is below.)
In and around the same time, there was another event where a piece of the seabed about the size of Iceland, slipped off the continental shelf, west of Norway. The geological event resulted in giant tsunamis with waves up to 20 meters high [about 6 stories] that washed over Iceland, Greenland,
Norway, Faroe Islands, and the UK.
New research shows how tsunamis hit Northwest Europe 8200 years ago, ravaging Stone Age coastal communities as far south as Denmark.
www.sciencenordic.com
The idea is, this information went through a few millennia and like anything else, the picture changed over time until it popped up in religious texts as a completely different story.
I've never posted a video in here, so if I did this wrong the link is: