What is the purpose of a safety stop during a dive?

The primary purpose of a safety stop during a dive is to allow for nitrogen off-gassing before ascending to the surface. When divers descend to depth, nitrogen from the breathing gas is absorbed into the body's tissues under increased pressure. As divers ascend, the pressure decreases, and the nitrogen absorbed can form bubbles if not released properly.

A safety stop, typically performed at a depth of around 15 to 20 feet for three to five minutes, provides time for nitrogen to safely off-gas from the body. This practice reduces the risk of decompression sickness, or "the bends," which can occur if a diver ascends too rapidly after spending time at depth.

The other options, while they may seem related to diving in general, do not address the crucial physiological aspect of nitrogen management in the body's tissues during ascent. Taking a break and hydrating, resetting a depth gauge, or increasing dive depth do not contribute to preventing decompression sickness, making them irrelevant in the context of safety stops.