What is the standard procedure for a controlled ascent?

The standard procedure for a controlled ascent emphasizes the importance of ascending slowly to prevent decompression sickness, which can occur when ascending too quickly. Ascending no faster than a specified rate, such as 9-18 meters per minute, allows the body to off-gas excess nitrogen that has been absorbed during the dive. Additionally, performing safety stops, typically at around 5 meters for a few minutes, further minimizes the risk of decompression illness by allowing any remaining nitrogen in the body to safely dissipate.

The other methods outlined would not adhere to safe ascent practices. Rapid ascents or direct ascents to the surface without stops can increase the risk of decompression sickness, as the body does not have adequate time to eliminate the nitrogen it has absorbed at depth. Ascending at varying speeds lacks consistency and could result in unsafe ascent rates, so maintaining a steady, controlled pace is critical in the context of safe diving practices.