why do deep sea divers have to swim slowly to the surface
What causes 'the bends'? If a SCUBA diver stays under water, say at a depth of 100 feet (about 30 meters), for a certain period of time, some amount of nitrogen from the air will dissolve in the water in his or her body. If the diver were to swim quickly to the surface, it is just like uncorking a bottle of soda -- the gas is released.