It was probably real and most likely covered the known world at that time. Remember, back then people were very isolated.
"Sediment layers suggest that 7,500 years ago Mediterranean water roared into the Black Sea"
Sediment layers suggest that 7,500 years ago Mediterranean water roared into the Black Sea
www.smithsonianmag.com
"It was this event that Pitman and Ryan believe could be the flood recorded in the Book of Genesis. The salt water poured through the deepening channel, creating a waterfall 200 times the volume of Niagara Falls (anyone who has ever traveled to the base of the falls on the Maid of the Mist will have a sense of the power involved). In a single day enough water came through the channel to cover Manhattan to a depth at least two times the height of the World Trade Center, and the roar of the cascading water would have been audible at least 100 miles away. Anyone living in the fertile farmlands on the northern rim of the sea would have had the harrowing experience of seeing the boundary of the ocean move inland at the rate of a mile a day."
I would not believe everything the Bible says but I also do not discount everything in it.