The Bible describes a great flood that occurred during the time of Noah. The Lord declared that
And, behold, I, even I, do bring a flood of waters upon the earth, to destroy all flesh, wherein is the breath of life, from under heaven: and every thing that is in the earth shall die (Genesis 6:17).
Noah was commanded to build an ark that was approximately 450 feet long, 75 feet wide, and 45 feet high (Genesis 6:15). Noah was told to bring into the ark all animals and fowls (Genesis 6:19-20, 7:2-3).
And the flood was forty days upon the earth; and the waters increased, and bare up the ark, and it was lift up above the earth.
And the waters prevailed exceedingly upon the earth: and all the high hills, that were under the whole heaven were covered.
Fifteen cubits upward did the waters prevail; and the mountains were covered.
And all flesh died that moved upon the earth, both of fowl, and of cattle, and of beast, and of every creeping thing that creepeth upon the earth, and every man:
All in whose nostrils was the breath of life , of all that was in the dry land, died.
And every living substance was destroyed which was upon the face of the ground, both man, and cattle, and the creeping things, and the fowl of the heaven: and they were destroyed from the earth and Noah only remained alive, and they that were with him in the ark.
And the waters prevailed upon the earth and hundred and fifty days. (Genesis 7:17, 19-24)
The story of Noah and the flood is a basic part of Christianity and thus of Mormonism. It is an interesting story, but a confusing story, and not all Latter-day Saints have the same interpretation of it. Most LDS that I have talked with take the story literally, that the whole planet was covered with a flood, and that Noah literally took mating pairs of all the animals and birds on the planet into the ark. Some LDS accept the story as being real but think the flood was a regional flood and didn't cover the whole earth, and that Noah took mating pairs of the animals and birds that were common to his area. Other LDS think the story is an allegory to teach the moral principles of faith and obedience to God.
The Lord through latter-day revelation, as recorded in the Doctrine & Covenants, refers to Noah as a real person, and I accept him as such. However, I have a problem with accepting the story of the flood as a global flood. My personal belief is that the story as recorded in Genesis was a regional flood rather than a global flood.