What is the purpose of a safety stop during ascent?

The purpose of a safety stop during ascent primarily serves to allow nitrogen to be released from the body. As divers descend and spend time underwater, their bodies absorb nitrogen due to the increased pressure. When ascending, especially to shallower depths, the pressure decreases, and if a diver ascends too quickly, the rapid change can lead to nitrogen bubbles forming in the body, resulting in decompression sickness.

A safety stop, typically conducted at a depth of around 15 to 20 feet (about 5 to 6 meters) for about three to five minutes at the end of a dive, provides an opportunity for excess nitrogen to off-gas safely. This gradual ascent and pause help ensure that the nitrogen absorbed can be released without causing harm, making it a crucial part of safe diving practices.

While allowing divers to rest or check equipment functionality can be beneficial, they are secondary benefits. Conserving air supply is also not a direct purpose of a safety stop; rather, it is about managing nitrogen levels in the body to prevent decompression illness. Therefore, the core rationale focuses on the physiological aspect of nitrogen release during decompression.