SDI Open Water Scuba Diver Practice Exam

What is the main purpose of a safety stop during ascent?

1. To check equipment function.

2. To allow for gas exchange.

3. To prevent equipment loss.

4. To reduce nitrogen absorption.

The correct answer is: To reduce nitrogen absorption.

The main purpose of a safety stop during ascent is to allow for gas exchange and to help prevent decompression sickness, more commonly known as "the bends." When divers ascend, the pressure decreases, and nitrogen, which has been absorbed into the body while diving, is released from tissue into the bloodstream. A safety stop, typically performed at around 15 to 20 feet (approximately 5 to 6 meters) for three to five minutes, gives the body additional time to off-gas the excess nitrogen that may have accumulated during the dive. This allows for a safer ascent and greatly reduces the risk of nitrogen bubbles forming in the body, which can lead to serious health issues. While checking equipment function and preventing equipment loss are important considerations during a dive, they are not the primary reasons for implementing a safety stop. Similarly, while reducing nitrogen absorption is an objective of controlled diving practices, the direct function of a safety stop specifically targets the elimination of nitrogen from the body post-dive, rather than affecting absorption levels during the dive itself.