This is cool link.

The Flood

There is no evidence that a world wide flood happened, but there is evidence that localized flooding happened, that at the time people would have thought that the whole earth was flooded because to them what they perceived (their surroundings) was the whole earth. Anyways, if whole earth was deluged by water, here is the math.

Since the Earth is only 10,000 years old not much geological change has happened, so I took Mt. Everest as the tallest place on earth, and then added 40 cubits to that height. There is some contention of what a cubit so I just took an average. They think a cubit was between 43 to 56 centimeters long so:

43 + 56 / 2 = 49.5 cm
49.5 cm = 0.000495 km

first the volume of the earth:

V = 4/3 x pi x r³
= (1.3 ) (3.14) (6,371)³
= 1055591332674.502 km³

second, volume of earth plus added the height of Mt Everest

Mt Everest = 8.848 km, add that to the radius of the earth
6371.0 + 8.848 + .000495 = 6379.85 km

V_{earth + Mt. Everest} = 4/3 x pi x r³
= (1.3)x(3.14)x(6378.85)³
= 1059995436864.56 km³

Volume of water fallen = V_earth - V _{e + Mt Everest}
= 4404104190.06 km³

converting that to gallons of water = 1.163 x 10²¹

That is one more decimal place that all the water on the earth, and if that much water vapor was in the atmosphere, the atmospheric pressure would have been so great that life could not exist on the earth.