Why should divers avoid rapid ascents?

Rapid ascents should be avoided primarily to prevent decompression sickness (DCS), commonly known as "the bends." When a diver ascends too quickly, the reduction in pressure can cause dissolved gases, particularly nitrogen, to form bubbles in the body. Under higher pressures (like those experienced underwater), nitrogen is absorbed into the body’s tissues, but as the pressure decreases too quickly, nitrogen comes out of solution and can accumulate in various tissues, leading to DCS. This condition can result in serious health issues, including joint pain, paralysis, or even death.

To mitigate the risks associated with rapid ascents, divers are trained to ascend slowly, typically following the guidelines for safe ascent rates and to make safety stops as needed, allowing the excess nitrogen in their bodies to safely off-gas without causing bubbles to form.

The other options, while related to good diving practices, do not address the primary risk associated with rapid ascents. Conserving air supply is more related to diving techniques and management, buoyancy control pertains to maintaining position in the water column, and enhancing underwater visibility does not directly relate to ascent rates.