If the Black Sea and Mediterranean Sea were once valleys or low areas and flooded at once, that would be a significant flood.
The Black Sea Flood HypothesisI've always liked the one of the flooding of the Mediterranean Basin myself, with the Gibralter Wall cracking and flooding.
The Black Sea flood *could* be the source of a good many of the surviving flood stories from the surrounding region, but the Mediterranean flood was over 5 million years ago — no human witnesses.
I just finished rereading “Noah’s Flood” by Ryan and Pitman; the reason I’d started it again was that I’m a little under the weather right now and it was within reach. :’)