Why are our bodies not crushed by the large pressure exerted by the atmosphere?

Because the atmosphere also pressurize the body. Diving down 100 meters will pressurize the gasses in the body and they will compress, like the air in our lungs and if the lung volume gets below half a litre the lungs can get partly filled with blood plasma. But sorry no bone crushing. But if you take a big breath and hold it while you ascend from 100 meters to the surface, your ribs may start to break –