The myth of the Great flood started in Sumer, with the “Epic of Gilgamesh”(around 2600 BC), the story then evolved into a similar Babylonian legend, the hero being Utnapishtim.
The story shares many similarities with the biblical story of Noah and the ark, in both stories there is a great flood and a god warns a worthy person that the flood will destroy all mankind, both Utnapishtim and Noah build giant wooden boats and load all the animals of the world on to the arks. In both cases the ark came to rest on top of a mountain, and birds were released in order to determine weather the water level had fallen.
The story of Noah was probably adapted from the “Epic of Gilgamesh” by the Israelites, after learning the story when they were enslaved by the Babylonians. When the Israelites returned from Babylonia they may have reworked the story and “Noah and the ark” became the new “Epic of Gilgamesh”.
In Greek culture there is also a story similar to that of Noah, Deucalion the hero of the Greek myth is associated with the grapevine and viniculture like Noah who according to Genesis “was the first person to plant the vine”.
The Greeks my have adapted their myth from the Israelite story of Noah, The Israelites were a nomadic people and the story would have been carried with them during their travels, the story may have been carried to Greece by word of mouth, being embellished to suit their culture along the way.
The flood story appears in other cultures such as the indigenous peoples of America, Australia, Polynesia, Melanesia, and places like India, Tibet, Kashmir and Lithuania. Depending in which context this fact is looked at it can mean different things, if a believer of the bible was to look at this fact they would see it as solid truth that Noah and the flood is a true story.
The fact that all these cultures could have a story that involves the same basic elements could also form the basis of an argument that this particular story of a power higher than our own, sending an element we cannot control to destroy the evil on the earth is embedded in humanity, a story to scare us into being good people like Noah and Utnapishtim.
Physical proof of a large flood has been found by Leonard Woolley at the mouth of the Tigris River at Ur, after looking at the strata, he discovered a silt layer 2.4 meters above sea level, the water level to cause this much silt was estimated to be over 120 meters.
Leonard Woolley was positive his find was proof that the great flood was a reality, but the bible accounts that the flood waters were so high they covered every mountain on earth, this would include Mt Everest which is 8,848 meters high, the floodwaters if they covered the entire earth, would come nowhere near to covering the summit.
It is more likely that the “Epic of Gilgamesh” was a way for the Sumerians and the Babylonians to explain the flood, and overtime the story became divine.
Many conclusions can be drawn from the fact that the “Great Flood” story is so widespread, perhaps the most obvious being that there was one, but in the terms of how it is described in myths and legends goes against logic.
The most probable conclusion is that human kind are scared of a power greater than them, and flooding by unstoppable rain seemed a likely way of that power destroying the evil on earth, because the “good” people would have a chance to be saved.