According to Genesis, on which day of Noah's six-hundredth year did the Flood begin?

According to Genesis, the Flood began on the seventeenth day of the second month of Noah's six-hundredth year.

Genesis 7:11 gives this date while describing the breaking open of the great deep and the opening of the heavens. It follows the earlier statement that Noah was 600 years old when the Flood waters came. The date is part of a sequence of calendar markers in the story.

Genesis later records the ark resting on the mountains of Ararat on the seventeenth day of the seventh month. The waters continued to decrease, and the narrative eventually reaches the first day of the first month of Noah's 601st year, when he removed the ark's covering and saw that the ground was drying.

Modern calendars cannot convert the biblical date with certainty because the ancient calendar system and month lengths are not fully specified here. The answer is therefore best given in the form used by Genesis: a day, month, and regnal-style year of Noah's life.