I believe it was worldwide - it covered the face of the earth - and the LORD said, I will destroy man whom I have created from the "face of the earth" both man, and beast, and the creeping thing, and the fowls of the air; . . . Gen. 6:7
And all "flesh" died that moved upon the earth, both of fowl, and of cattle, and of beast, and of every creeping thing that creeps upon the earth, and every man: ALL in whose nostrils was the breath of life, of all that was in the dry land, died. Gen 7:21-22
. . . at the end of the hundred and fifty days the waters were abated. And the ark rested in the seventh month on the seventeenth day of the month upon the mountains of Ararat. And the water decreased continually until the tenth month: in the tenth month on the first day of the month were the tops of mountains seen. Gen 8:3b-5
And the dove came in to him in the evening; and, lo, in her mouth was an olive leaf plucked off: so Noah knew that the waters were abated from off the earth. Gen. 8:11
And it came to pass in the six hundredth and first year, in the first month, the first day of the month, the waters were dried up from off the earth . . . and in the second month, on the seven and twentieth day of the month, was the earth dried. Gen. 8:13
The thing that amazes me is that Noah and his family with all those animals were on that ark for 1 year and 10 days!!!!