What does the term "safe ascent rate" refer to?

The term "safe ascent rate" refers to the speed at which a diver should ascend to reduce the risk of decompression sickness (DCS). As a diver ascends, the pressure around them decreases, and nitrogen that has been absorbed into the body's tissues must be released safely to avoid the formation of gas bubbles, which can lead to DCS. The commonly recommended safe ascent rate is typically around 30 feet per minute, allowing for controlled decompression and the opportunity to make safety stops, which further enhances safety by providing additional time for nitrogen to be eliminated from the body.

In this context, the other choices do not accurately define "safe ascent rate." The maximum depth a diver can reach pertains to limits based on training and safety, the time allowed for a surface interval is related to pre-dive planning and nitrogen off-gassing, and the technique for equalizing pressure deals with the prevention of barotrauma during descent and ascent, not specifically with the ascent speed itself.