Why is it essential to ascend slowly after a dive?

Ascending slowly after a dive is crucial primarily to allow time for gases, particularly nitrogen, to safely exit the body. During a dive, the body absorbs nitrogen under increased pressure. If a diver ascends too quickly, the drop in pressure can cause the dissolved nitrogen to form bubbles in the body, leading to decompression sickness, also known as "the bends." This condition can result in severe injury or even be life-threatening.

By ascending gradually, divers give their bodies enough time to expel nitrogen safely through breathing. It is typically recommended to ascend no faster than 18 meters (60 feet) per minute and to perform safety stops at various depths, particularly after deeper dives, to further mitigate the risk of decompression sickness. This practice helps ensure a safer and more comfortable diving experience, emphasizing the importance of controlled ascent rates in diving safety protocols.