The catastrophic destruction of men and animals by an overwhelming flood in the days of Noah, 2370 B.C.E. This greatest cataclysm in all human history was sent by Jehovah because wicked men had filled the earth with violence. The survival of righteous Noah and his family, eight souls in all, together with selected animals, was by means of a huge ark, or chest.​—Ge 6:9–9:19; 1Pe 3:20; see ARK No. 1; NOAH No. 1.

Extent of the Deluge. This was no local flash flood or cloudburst. In fact, the Greek word used in the Bible to refer to the Flood, or Deluge, is ka·ta·kly·smosʹ, a cataclysm. (Lu 17:27, ftn) Local floods come and go in a matter of days; this one lasted over a year, the greater portion of which was required for the water to subside. How unreasonable to believe that Noah spent perhaps 50 years building a huge vessel of approximately 40,000 cu m (1,400,000 cu ft) for the survival of his family and a few animals through a mere local flood! If only a comparatively small area was affected, why the need of bringing into the ark specimens of “every living creature of every sort of flesh” in order to “preserve offspring alive on the surface of the entire earth”? (Ge 6:19; 7:3) Definitely this was a global deluge, the like of which had never occurred before nor has since. “The waters overwhelmed the earth so greatly that all the tall mountains that were under the whole heavens came to be covered. Up to fifteen cubits [c. 6.5 m; 22 ft] the waters overwhelmed them and the mountains became covered.” (Ge 7:19, 20) “The end of all flesh has come before me,” Jehovah said, hence “I will wipe every existing thing that I have made off the surface of the ground.” And it was just so. “Everything in which the breath of the force of life was active in its nostrils, namely, all that were on the dry ground, died . . . only Noah and those who were with him in the ark kept on surviving.”​—Ge 6:13; 7:4, 22, 23.

Timing of the Deluge. The Deluge did not come suddenly without warning. Years of time were spent building the ark, time that Noah the “preacher of righteousness” also used in warning that wicked generation. (2Pe 2:5) Finally the time limit was up “in the six hundredth year of Noah’s life, in the second month, on the seventeenth day of the month.” The “male and female of every sort of flesh” had been brought into the ark with Noah’s family, as well as a sufficient food supply for all, and “after that Jehovah shut the door.” Then “the floodgates of the heavens were opened.” (Ge 7:11, 16) There was an incessant torrential downpour for “forty days and forty nights”; “the waters continued overwhelming the earth” a hundred and fifty days. (Ge 7:4, 12, 24) Five months after the downpour began, the ark “came to rest on the mountains of Ararat.” (Ge 8:4) It was nearly two and a half months later before “the tops of the mountains appeared” (Ge 8:5), another three months before Noah removed the ark’s covering to see that the earth had practically drained (Ge 8:13), and nearly two months later when the door was opened and the survivors set foot on dry ground once again.​—Ge 8:14-18.

Noah and his family entered the ark in the 600th year of Noah’s life, the 2nd month (October-November), the 17th day. (Ge 7:11) One year later (a year consisting of 360 days) was the 17th day, 2nd month, 601st year. Ten days after that would be the 27th day of the 2nd month, when they came out; a total of 370 days, or parts of 371 separate days, spent in the ark. (Ge 8:13, 14) In the log that Noah kept, it appears he used months of 30 days each, 12 of them equaling 360 days. In this way he avoided all the complicated fractions involved had he used strictly lunar months consisting of slightly more than 29 1⁄2 days. That such calculations were used in the account is evident from the fact that a five-month period consisted of 150 days.​—Ge 7:11, 24; 8:3, 4.

The Floodwaters. It has been said that if all the moisture in the atmosphere were suddenly released as rain it would not amount to even a couple of inches if spread over the earth’s surface. So from what source was this vast deluge of Noah’s day? According to the Genesis account, God said to Noah: “Here I [Jehovah] am bringing the deluge [or, “heavenly ocean”; Heb., mab·bulʹ] of waters upon the earth.” (Ge 6:17, ftn) Describing what happened, the next chapter says: “All the springs of the vast watery deep were broken open and the floodgates of the heavens were opened.” (Ge 7:11) So overwhelming was the Deluge that “all the tall mountains that were under the whole heavens came to be covered.”​—Ge 7:19.

Where did this “heavenly ocean” come from? The Genesis account of creation tells how on the second “day” Jehovah made an expanse about the earth, and this expanse (called “Heaven”) formed a division between the waters below it, that is, the oceans, and the waters above it. (Ge 1:6-8) The waters suspended above the expanse evidently remained there from the second “day” of creation until the Flood. This is what the apostle Peter was  talking about when he recounted that there “were heavens from of old and an earth standing compactly out of water and in the midst of water by the word of God.” Those “heavens” and the waters above and beneath them were the means that God’s word called into operation, and “by those means the world of that time suffered destruction when it was deluged with water.” (2Pe 3:5, 6) Various explanations have been offered as to how the water was held aloft until the Flood and as to the processes that resulted in its falling. But these are only speculative. The Bible says simply that God made the expanse with waters above it and that he brought the Deluge. His almighty power could easily accomplish it.

Since, as the Genesis account says, “all the tall mountains” were covered with water, where is all that water now? Evidently it is right here on the earth. It is believed that there was a time when the oceans were smaller and the continents were larger than they are now, as is evidenced by river channels extending far out under the oceans. It should also be noted that scientists have stated that mountains in the past were much lower than at present, and some mountains have even been pushed up from under the seas. As to the present situation, it is said that “there is ten times as much water by volume in the ocean as there is land above sea level. Dump all this land evenly into the sea, and water would cover the entire earth, one and one-half miles deep.” (National Geographic, January 1945, p. 105) So, after the floodwaters fell, but before the raising of mountains and the lowering of seabeds and before the buildup of polar ice caps, there was more than enough water to cover “all the tall mountains,” as the inspired record says.​—Ge 7:19.

Effect on the Earth. With the Deluge great changes came, for example, the life span of humans dropped very rapidly. Some have suggested that prior to the Flood the waters above the expanse shielded out some of the harmful radiation and that, with the waters gone, cosmic radiation genetically harmful to man increased. However, the Bible is silent on the matter. Incidentally, any change in radiation would have altered the rate of formation of radioactive carbon-14 to such an extent as to invalidate all radiocarbon dates prior to the Flood.

With the sudden opening of the ‘springs of the watery deep’ and “the floodgates of the heavens,” untold billions of tons of water deluged the earth. (Ge 7:11) This may have caused tremendous changes in earth’s surface. The earth’s crust, which is relatively thin and varied in thickness, is stretched over a rather plastic mass thousands of kilometers in diameter. Hence, under the added weight of the water, there was likely a great shifting in the crust. In time new mountains evidently were thrust upward, old mountains rose to new heights, shallow sea basins were deepened, and new shorelines were established, with the result that now about 70 percent of the surface is covered with water. This shifting in the earth’s crust may account for many geologic phenomena, such as the raising of old coastlines to new heights. It has been estimated by some that water pressures alone were equal to “2 tons per square inch,” sufficient to fossilize fauna and flora quickly.​—See The Biblical Flood and the Ice Epoch, by D. Patten, 1966, p. 62.

What evidence proves that there truly was a global deluge?

Other possible evidence of a drastic change: Remains of mammoths and rhinoceroses have been found in different parts of the earth. Some of these were found in Siberian cliffs; others were preserved in Siberian and Alaskan ice. (PICTURE, Vol. 1, p. 328) In fact, some were found with food undigested in their stomachs or still unchewed in their teeth, indicating that they died suddenly. It is estimated, from the trade in ivory tusks, that bones of tens of thousands of such mammoths have been found. The fossil remains of many other animals, such as lions, tigers, bears, and elk, have been found in common strata, which may indicate that all of these were destroyed simultaneously. Some have pointed to such finds as definite physical proof of a rapid change in climate and sudden destruction caused by a universal flood. Others, however, favor explanations for the death of these animals that do not involve an earth-wide catastrophe. Proof that the Flood occurred is not dependent on such fossils and frozen animal remains.

Flood Legends. Such a cataclysm as the Deluge, which washed the whole world of that time out of existence, would never be forgotten by the survivors. They would talk about it to their children and their children’s children. For 500 years after the Deluge, Shem lived on to relate the event to many generations. He died only ten years before the birth of Jacob. Moses preserved the true account in Genesis. Sometime after the Flood, when God-defying people built the Tower of Babel, Jehovah confused their language and scattered  them “over all the surface of the earth.” (Ge 11:9) It was only natural that these people took with them stories of the Flood and passed them on from father to son. The fact that there are not merely a few but perhaps hundreds of different stories about that great Deluge, and that such stories are found among the traditions of many primitive races the world over, is a strong proof that all these people had a common origin and that their early forefathers shared that Flood experience in common.​—CHART, Vol. 1, p. 328.

These folklore accounts of the Deluge agree with some major features of the Biblical account: (1) a place of refuge for a few survivors, (2) an otherwise global destruction of life by water, and (3) a seed of mankind preserved. The Egyptians, the Greeks, the Chinese, the Druids of Britain, the Polynesians, the Eskimos and Greenlanders, the Africans, the Hindus, and the American Indians​—all of these have their Flood stories. The International Standard Bible Encyclopedia (Vol. 2, p. 319) states: “Flood stories have been discovered among nearly all nations and tribes. Though most common on the Asian mainland and the islands immediately south of it and on the North American continent, they have been found on all the continents. Totals of the number of stories known run as high as about 270 . . . The universality of the flood accounts is usually taken as evidence for the universal destruction of humanity by a flood and the spread of the human race from one locale and even from one family. Though the traditions may not all refer to the same flood, apparently the vast majority do. The assertion that many of these flood stories came from contacts with missionaries will not stand up because most of them were gathered by anthropologists not interested in vindicating the Bible, and they are filled with fanciful and pagan elements evidently the result of transmission for extended periods of time in a pagan society. Moreover, some of the ancient accounts were written by people very much in opposition to the Hebrew-Christian tradition.”​—Edited by G. Bromiley, 1982.

In times past, certain primitive people (in Australia, Egypt, Fiji, Society Islands, Peru, Mexico, and other places) preserved a possible remnant of these traditions about the Flood by observing in November a ‘Feast of Ancestors’ or a ‘Festival of the Dead.’ Such customs reflected a memory of the destruction caused by the Deluge. According to the book Life and Work at the Great Pyramid, the festival in Mexico was held on the 17th of November because they “had a tradition that at that time the world had been previously destroyed; and they dreaded lest a similar catastrophe would, at the end of a cycle, annihilate the human race.” (By Professor C. Piazzi Smyth, Edinburgh, 1867, Vol. II, pp. 390, 391) Notes the book The Worship of the Dead: “This festival [of the dead] is . . . held by all on or about the very day on which, according to the Mosaic account, the Deluge took place, viz., the seventeenth day of the second month​—the month nearly corresponding with our November.” (By J. Garnier, London, 1904, p. 4) Interestingly, the Bible reports that the Flood began “in the second month, on the seventeenth day of the month.” (Ge 7:11) That “second month” corresponds to the latter part of October and the first part of November on our calendar.

Scriptural Confirmation. Stronger evidence of the historicalness of the Deluge than the pagan traditions of primitive people is the endorsement other Bible writers gave under inspiration. The only other place where the same Hebrew word (mab·bulʹ, deluge) occurs outside the Genesis account is in David’s melody where he describes Jehovah as seated “upon the deluge.” (Ps 29:10) However, other writers make reference to and confirm the Genesis account, as, for example, Isaiah. (Isa 54:9) Ezekiel also endorses the historicity of Noah. (Eze 14:14, 18, 20) Peter draws heavily upon the Deluge account in his letters. (1Pe 3:20; 2Pe 2:5; 3:5, 6) Paul testifies to the great faith Noah displayed in constructing the ark for the survival of his household. (Heb 11:7) Luke lists Noah in the lineage of Messiah’s forebears.​—Lu 3:36.

Even more significant is what Jesus said about the days of the Deluge, as recorded by both Luke and Matthew. Far more than just a simple endorsement of the veracity of the Deluge account, Jesus’ words show the pictorial and prophetic significance of those ancient events. In answer to the disciples’ question, “What will be the sign of your presence and of the conclusion of the system of things?” Jesus said, among other things: “For just as the days of Noah were, so the presence of the Son of man will be. For as they were in those days before the flood, eating and drinking, men marrying and women being given in marriage, until the day that Noah entered into the ark; and they took no note until the flood came and swept them all away, so the presence of the Son of man will be.” (Mt 24:3, 37-39; Lu 17:26, 27) There is, therefore, abundant evidence from the inspired Holy Scriptures themselves to support the authenticity and genuineness of the Deluge account. It does not  rest on mere traditions of men, on the folklore of primitive people, or on geologic and archaeological findings.