The Flood was a real event. God caused it in order to destroy the wicked people, but he had Noah build an ark to preserve the good people and the animals. (Genesis 6:11-20) We can believe that the Flood really happened because it is recorded in Scripture, which “is inspired of God.”​—2 Timothy 3:16.

•  Fact or fable?

•  Why did the Flood happen?

•  Did people know that the Flood was coming?

•  What did Noah’s ark look like?

•  How long did it take Noah to build the ark?

•  Great flood stories, myths, and legends

 The Bible indicates that Noah was a real person and that the Flood was a real event, not a fable or a myth.

•   Bible writers believed that Noah was a real person. For example, the Bible writers Ezra and Luke were skilled historians who included Noah in genealogies of the nation of Israel. (1 Chronicles 1:4; Luke 3:36) The Gospel writers Matthew and Luke recorded Jesus’ remarks about Noah and the Flood.—Matthew 24:37-39; Luke 17:26, 27.

   Also, the prophet Ezekiel and the apostle Paul cited Noah as an example of faith and righteousness. (Ezekiel 14:14, 20; Hebrews 11:7) Would it make sense for these writers to point to a mythical person as an example to follow? Clearly, Noah and other men and women of faith are examples to imitate because they were real people.—Hebrews 12:1; James 5:17.

•   The Bible gives specific details about the Flood. The Bible account of the Flood does not begin with anything like “Once upon a time,” as if it were a fairy tale. Rather, the Bible states the year, the month, and the day that events connected with the Flood happened. (Genesis 7:11; 8:4, 13, 14) It also gives the dimensions of the ark that Noah built. (Genesis 6:15) These details show that the Bible presents the Flood as a fact, not as a fable.

 According to the Bible, before the Flood “man’s wickedness was great.” (Genesis 6:5) It adds that “the earth had become ruined in the sight of the true God” because it was filled with violence and sexual immorality.—Genesis 6:11; Jude 6, 7.

 The Bible says that much of this trouble was caused by wicked angels who left heaven to have relations with women. These angels had offspring called Nephilim, who wreaked havoc on humankind. (Genesis 6:1, 2, 4) God decided to clear the earth of wickedness and allow good people to have a fresh start.—Genesis 6:6, 7, 17.

 Yes. God told Noah what would happen and instructed him to build an ark to preserve his family and the animals. (Genesis 6:13, 14; 7:1-4) Noah warned people of the coming destruction, but they ignored his warnings. (2 Peter 2:5) The Bible says: “They took no note until the Flood came and swept them all away.”—Matthew 24:37-39.

 The ark was a large rectangular chest, or box, about 133 meters (437 ft) long, 22 meters (73 ft) wide, and 13 meters (44 ft) high. a The ark was made out of resinous wood, and it was covered with tar inside and out. It had three stories, or decks, and a number of compartments. There was a door in the side of the ark and evidently a window along the top. It seems likely that the ark had a roof that peaked in the middle with a slight pitch to allow water to run off.—Genesis 6:14-16.

 The Bible does not say how long it took Noah to build the ark, but it seems that he spent several decades building it. Noah was more than 500 years old when his first son was born, and he was 600 years old when the Flood occurred. b—Genesis 5:32; 7:6.

 God told Noah to build the ark after his three sons were grown and married, which could have taken some 50 or 60 years. (Genesis 6:14, 18) Based on this possibility, it seems reasonable to conclude that the ark could have taken 40 or 50 years to complete.