In the six hundredth year of Noah's life, in the second month, on the seventeenth day of the month, on the same day all the fountains of the great deep burst open, and the floodgates of the sky were opened. (Genesis 7:11)Final preparations for the ark were made. Methuselah died. All the animals were loaded on the ark. God sent a massive flood. All of humanity died, except for Noah's household. The waters rose high above the mountains— then the waters began to recede. And yes, all of that happened (and those are just some of the major events) within one year— and to be exact, the year was 2349 BC (according to James Ussher's calculations).
For 120 years, Noah had worked towards the construction of an enormous ship. Doubtless, those years passed with both happiness and sadness. Happiness because over those 120 years, Noah had become a father of three sons: Shem, Ham, and Japheth. Sadness because over those 120 years, the pre-flood world continued in its rebellion against God.
In 2349 BC (1656 years after creation), Noah was still faithful. He was still obedient to God. Despite the death of his father Lamech just 4 years ago, Noah continued to press forward. Only one of Noah's ancestors was still alive: Methuselah.
Known as the oldest recorded man in human history, it is unknown whether Methuselah died shortly before the flood or in the flood. Perhaps he died a month before the flood, or perhaps he died in the 7 days before the flood. Either way, Methuselah was the only living ancestor Noah had left on the earth. Adam had long ago died, and Methuselah was likely the last man left on the face of the earth who had met him in person (for more information see Methuselah: The Oldest Person (969 Short Years)).
State of the World (2349 BC): The Flood (Part 2) - Genesis 7:11
State Of The World (2469 BC): 120 Years Before The Flood - Genesis 6:3
A Short Account of the Ark's Final Preparation - Genesis 7:6-9
7 More Days - Genesis 7:4-5
Noah's Obedience - Genesis 6:22