What physiological condition should divers monitor to avoid decompression sickness?

Monitoring hydration levels is crucial for divers to avoid decompression sickness. Decompression sickness, commonly known as "the bends," occurs when a diver ascends too quickly and nitrogen bubbles form in the bloodstream and tissues due to reduced pressure. Proper hydration helps maintain blood viscosity, which can facilitate better circulation and assist the body in efficiently eliminating nitrogen as it comes out of solution during ascent. Being well-hydrated helps to avoid thickening of the blood and reduces the risk of bubbles forming in the first place.

Inner ear pressure, temperature of the water, and blood pressure are also important physiological factors but are less directly linked to the prevention of decompression sickness. The inner ear pressure can affect balance and may contribute to barotrauma, the water temperature can influence comfort and other physiological responses, and blood pressure is a general indicator of cardiovascular health but does not specifically address the nitrogen absorption and release processes critical to preventing decompression sickness.