In the six hundredth year of Noah’s life, on the seventeenth day of the second month—on that day all the springs of the great deep burst forth, and the floodgates of the heavens were opened.
Genesis 7:11 (NIV)
I find it interesting that after discussions about “approximate years” and “outrageous ages” of the men listed in the genealogy of Genesis 5 (suggesting that the dates are vague approximations or merely symbols of "very long times"), we are presented with this extremely specific day of the flood.