The Great Flood

Genesis 6:13 : "...The end of all flesh has come before Me; for the earth is filled with violence because of them; and behold, I am about to destroy them with the earth."

"The Deluge", by John Martin, 1834. 

A flood myth or deluge myth is a symbolic narrative in which a great flood is sent by a deity, or deities, to destroy civilization in an act of divine retribution. Parallels are often drawn between the flood waters of these myths and the primeval waters found in certain creation myths, as the flood waters are described as a measure for the cleansing of humanity, in preparation for rebirth. Most flood myths also contain a culture hero, who strives to ensure this rebirth.The flood myth motif is widespread among many cultures as seen in the Mesopotamian flood stories, the Puranas, Deucalion in Greek mythology, the Genesis flood narrative, and in the lore of the K'iche' and Maya peoples of Central America, and the Muisca people in South America.
The Great Flood refers to the most catastrophic flood and the most catastrophic
geological event that has ever taken place in human history.
Virtually nothing historical, from writings to civilization to long-living organisms like trees, has survived from before about 3000 or 3300 B.C., approximates date given to the Great Flood.Today 60% of Americans accept as truth the Biblical account of the Great Flood,and most cultures record a world-destroying flood in their oral or written histories.

Mythologies

The Great Flood, by
anonymous painter

The Mesopotamian flood stories concern the epics of Ziusudra, Gilgamesh, and Atrahasis. In the Sumerian King List, it relies on the flood motif to divide its history into preflood and postflood periods. The preflood kings had enormous lifespans, whereas postflood lifespans were much reduced. The Sumerian flood myth found in the Deluge tablet was the epic of Ziusudra, who heard the Divine Counsel to destroy humanity, in which he constructed a vessel that delivered him from great waters.In the Atrahasis version, the flood is a river flood.
Assyriologist George Smith translated the Babylonian account of the Great Flood in the 19th Century. Further discoveries produced several versions of the Mesopotamian flood myth, with the account that is closest to that in "Genesis 6–9" found in a 700 BC Babylonian copy of the Epic of Gilgamesh. In this work, the hero, Gilgamesh, meets the immortal man, Utnapishtim, and the latter describes how the god, Ea, instructed him to build a huge vessel in anticipation of a deity-created flood that would destroy the world; the vessel was not only intended for Utnapishtim, but was built to also protect his family, his friends and animals.
In Hindu mythology, texts such as the Satapatha Brahmana mention the puranic story of a great flood,wherein the Matsya Avatar of Vishnu warns the first man, Manu, of the impending flood, and also advises him to build a giant boat.
This flood was the means of God's judgment on mankind because of the evil in their heart and actions. God warned Noah that He was going to destroy the world with a flood, because of the wickedness of mankind. Noah was to build an ark and take his family and pairs of each kind of air-breathing animal in it in order to be saved from the flood.
After Noah and his family and all the creatures were on board, God shut the door of the ark. The flood was brought on by the bursting open of the fountains of the great deep and the opening of the floodgates of the sky. The rain lasted nearly six weeks (40 days and nights). The flood waters apparently continued to rise for 150 days, but it was just over a year before the waters had receded enough for the occupants of the ark to leave.
The ark came to rest on one of the mountains of Ararat. God used a rainbow in the clouds as a sign that he would never again destroy the world in a flood.\

Historicity
Ancient Shuruppak, Ur, Kish, Uruk, Lagash, and Ninevah all present evidence of flooding. However, the evidence comes from different times.In Israel, there is no such evidence of a widespread flood.
                                                              
Hypotheses

"The Deluge", frontispiece
 to Gustave Doré'

Adrienne Mayor's The First Fossil Hunters and Fossil Legends of the First Americans promoted the hypothesis that flood stories were inspired by ancient observations of seashells and fish fossils in inland and mountain areas. The ancient Greeks, Egyptians, Romans, and Chinese all documented the discovery of such remains in these locations; the Greeks hypothesized that Earth had been covered by water on several occasions, citing the seashells and fish fossils found on mountain tops as evidence of this history.
Speculation regarding the Deucalion myth has also been introduced, whereby a large tsunami in the Mediterranean Sea, caused by the Thera eruption (with an approximate geological date of 1630–1600 BC), is the myth's historical basis. Although the tsunami hit the South Aegean Sea and Crete it did not affect cities in the mainland of Greece, such as Mycenae, Athens, and Thebes, which continued to prosper, indicating that it had a local rather than a regionwide effect.
Another hypothesis is that a meteor or comet crashed into the Indian Ocean around 3000–2800 BC, created the 30 kilometres (19 mi) undersea Burckle Crater, and generated a giant tsunami that flooded coastal lands.
It has been postulated that the deluge myth may be based on a sudden rise in sea levels caused by the rapid draining of prehistoric Lake Agassiz at the end of the last Ice Age, about 8,400 years ago.
One of the latest, and quite controversial, hypotheses of long term flooding is the Black Sea deluge hypothesis, which argues for a catastrophic deluge about 5600 BC from the Mediterranean Sea into the Black Sea. This has been the subject of considerable discussion.

Source: http://www.conservapedia.com/Great_Flood
            http://en.wikipedia.org/wiki/Flood_myth