Scuba Diving International (SDI) Computer Nitrox Practice Exam

What is a decompression stop?

1. Continuing ascent to the surface without pause

2. Pausing at a fixed depth for a specified period

3. An emergency procedure for out-of-air situations

4. Descending to a greater depth to avoid nitrogen

The correct answer is: Pausing at a fixed depth for a specified period

A decompression stop is a critical procedure during ascent from a dive, where a diver pauses at a predetermined depth for a set amount of time. This practice is essential for allowing nitrogen, which accumulates in the body tissues during a dive, to safely off-gas and reduce the risk of decompression sickness, commonly known as "the bends." When a diver ascends too quickly, the rapid decrease in pressure can cause nitrogen bubbles to form in the tissues and bloodstream, resulting in potential injuries. By performing a decompression stop, the diver allows the body to adjust to the changing pressure in a controlled manner, ensuring that nitrogen is released gradually and safely. The duration and depth of the stop are usually determined based on the dive profile and the amount of nitrogen absorbed during the dive. In context, the other options do not accurately represent the concept of a decompression stop. Continuing ascent without pause does not allow for safe off-gassing; an emergency procedure for an out-of-air situation does not relate to the risks and safety needs associated with nitrogen saturation; and descending to a greater depth typically contradicts the principle of managing nitrogen elimination safely.