There are many flood myths. Every culture seems to have one. This has been taken by christians to be proof for Noah's flood. Of course, all the other flood stories have been handed down by word of mouth, and have been distorted over time. The biblical account being the only literally true version - yeah right! The biblical account is reckoned to be based on the Babylonian version, which is in turn based on the one referred to by the Sumerians in the Epic of Gilgamesh. The hypothesis I favour at the moment is that this story is based on an orally transmitted memory of the deluge back in the sixth millennium BC, when the salt waters of the Mediterranean Sea burst through the land barrier where Istanbul is now, and drowned the shores of the vast freshwater lake north of Turkey, to create today's Black Sea.
In Greek mythology there is the Ogygian flood, whose survivors are Deucalion and his wife Pyrrha. This flood, however, seems to date to a few generations before the main events of Greeks mythology such as the voyage of the Argonauts, the Theban wars, and of course, the Trojan war. A flood dating to 4,000 years previously is incompatible with Greek writings. A flood dating to 1628BC, on the other hand, is well within the timeframe. That's when Thera erupted according to ice cores excavated from the Greenland Ice Sheet. It caused a tsunami that devastated Crete, and drained then flooded the marshes of Northern Egypt, an event which may have been remembered as the parting of the waves in the Bible.
And what of Greece? The tsunami would have been as devastating to its coast as it was to Crete, and just as traumatic to the survivors as the Black Sea flooding was centuries before. And it has not gone unrecorded. My hypothesis is that the Ogygian flood of King Deucalion was the result of the Thera eruption, and not a distorted retelling of an earlier flood legend.
Two floods. Not one.