PADI Divemaster Certification Practice Exam

If a diver's ending pressure group is X after the second dive, what is the minimum surface interval needed before diving again?

1. 30 minutes

2. One hour

3. Two hours

4. Three hours

The correct answer is: One hour

The minimum surface interval needed for a diver whose ending pressure group is X after the second dive is indeed one hour. This stems from the tables used to determine the allowable surface interval based on the diver's pressure group and previous dive profiles. After any dive, divers enter a specific pressure group that indicates their nitrogen absorption level. As nitrogen is gradually off-gassed during the surface interval, divers need to allow sufficient time for this process before initiating another dive. The pressure group X typically indicates a nitrogen loading that requires a minimum surface interval for safety. In this case, a one-hour surface interval is the minimum recommended time before a diver can dive again after reaching pressure group X. This allows for adequate off-gassing, reducing the risk of decompression sickness, which can occur if divers descend too soon after significant nitrogen uptake. Other choices suggest longer surface intervals, which may provide additional safety but are not the minimum required time before diving again from pressure group X.