When diving, there are many factors to consider that can have an adverse effect on the body. The pressure of deep water can affect the body. This is known as barotrauma. There is also decompression sickness, which is more commonly known as the bends, and nitrogen narcosis. These different types of sickness are all related to nitrogen in the bloodstream. Diving down to low depths in the water affects how much nitrogen builds in your bloodstream. All three sicknesses can be deadly, even to the most experienced diver.

You get the bends from too fast of an ascent to the surface. Nitrogen bubbles build up in the bloodstream, affecting your joints. This will make you to want to bend your joints to relieve the pain. This is where the condition gets its name. Recovery from the bends can be done with aspirin, lots of fluids, and rest. Pure oxygen may be needed for mild cases. For severe cases, a recompression chamber, known as a hyperbaric chamber, is used for recovery and pain relief.

Barotrauma is caused by unequal air pressure between cavities in the body. Usually the sinus, ear, nose and lungs are affected. Cases can range from mild to severe. A severe case can entail a rupture of the membranes due to unequal pressure.

Nitrogen narcosis is caused when a diver descends to 100 feet or so. It is a euphoric feeling sometimes called "rapture of the deep". This narcosis affects people differently. Some people feel drunk or on good drugs. By giving in, you lose control of yourself and get into trouble easily. To get rid of this feeling, a diver needs to ascend until the feeling stops. Unlike drinking, nitrogen narcosis leaves instantly when ascending.