That was the rain. In Genesis 7 is says that after it stopped raining the waters prevailed upon the earth for 150 days before the Ark landed on Mt. Ararat. Then Noah waited 40 more days before the waters receded enough to land. And 3 months after landing the waters had completely receded. Lot of time to be paddling around.
Noah lived in the land of Ur (Southern Iraq). He landed at Mt. Ararat in Turkey, about 600 miles away (530 nautical miles).
If the ark was at sea for 190 days (40 rain days and 150 clear days), this means that Noah was traveling at an average speed of about 0.12 knots, essentially floating in place or gently drifting north for most of the time.
I'm not sure if this implies anything. He could have been circling at high speed or just drifting.
Still, if the whole earth had been covered in water, is it likely that after 190 days he'd end up only 530 nm to the north, or would global jet stream have swept him easterly after six months at sea?
On the other hand, if Noah gently drifted north for six months, does this imply that he was in an essentially land-locked sea?
-PJ