The surface area of a typical adult Caucasian man is about 1.8
square metres (19 square feet), so the total compressional force on the body surface
is nearly 20 tons. So, how is it we don't get crushed? Well, fortunately, most of the
tissues and fluids of the body are, on average, also at atmospheric pressure, so the
external force is balanced. When a diver descends into water the pressure on and
within the body increases, one effect of which is that nitrogen gas in any inhaled air
gets dissolved in the blood. If the diver returns too quickly to the surface the
nitrogen comes out of solution, forms bubbles in the blood and causes the 'bends',
which is life threatening.