Why is it essential to stay hydrated before a dive?

Staying hydrated before a dive is essential primarily because dehydration can significantly raise the risk of decompression sickness, also known as "the bends." When a diver ascends from a depth, dissolved gases (mainly nitrogen) that have been absorbed into the body tissues must be safely expelled. Proper hydration is necessary for healthy circulation and the elimination of these gases from the body. Dehydration can lead to thicker blood, which might impair the efficiency of blood flow and hinder the body's ability to expel this nitrogen properly, increasing the likelihood of these gases forming bubbles and causing decompression sickness.

This underscores the importance of maintaining hydration not just for overall health but as a critical safety factor in diving. In a diving context, being well-hydrated also assists the body in handling the physical stresses of diving, such as pressure changes and exertion, further ensuring a safer experience underwater.