Types of Diving -- Saturation Diving Page 2
During deep diving, a diver breathes a mixture of gases (compressed air or a combination of helium and oxygen; or helium, oxygen and nitrogen) at a pressure higher than that of air at the surface. As the diver breathes, a certain amount of nitrogen from compressed air is dissolved in the lungs. From the lungs, the blood carries this additional nitrogen to all the body's tissues. This condition can become potentially dangerous. Researchers discovered that in order to release nitrogen from the body safely, a deep-sea diver has to come to the surface slowly, a process known as "decompression." In general, the deeper or longer a diver is underwater, the longer it takes for the diver to decompress safely.