PADI Deep Diving Techniques & Planning 3 — Questions and Answers
Question 1: A diver notices their dive computer showing a flashing NDL warning at 80 feet. What is the correct action?
- Continue the dive until the NDL reaches zero
- Begin a controlled ascent immediately to a shallower depth (Correct answer)
- Descend deeper to reset the NDL
- Perform an emergency ascent to the surface
Correct answer: Begin a controlled ascent immediately to a shallower depth
When NDL is nearly exhausted, ascending to a shallower depth extends the NDL and reduces nitrogen absorption rate.
Question 2: What is the recommended minimum surface interval between repetitive deep dives?
- 15 minutes
- 30 minutes
- At least 1 hour, or as directed by dive tables/computer (Correct answer)
- 3 hours minimum always
Correct answer: At least 1 hour, or as directed by dive tables/computer
Surface intervals for repetitive diving should follow dive table or computer guidance, generally at least one hour, to allow adequate nitrogen off-gassing.
Question 3: Which gas law explains why air consumption increases dramatically during deep dives?
- Henry's Law
- Dalton's Law
- Boyle's Law (Correct answer)
- Charles's Law
Correct answer: Boyle's Law
Boyle's Law states that gas volume is inversely proportional to pressure, meaning each breath consumes more gas molecules at depth than at the surface.
Question 4: During a deep dive, a buddy suddenly becomes unresponsive at 90 feet. What is the first priority?
- Administer in-water rescue breathing immediately
- Signal other divers and note the time
- Establish positive buoyancy and begin a controlled ascent (Correct answer)
- Remove the buddy's weight belt immediately
Correct answer: Establish positive buoyancy and begin a controlled ascent
Establishing buoyancy and ascending with the unresponsive diver gets them to the surface where proper rescue breathing and emergency care can begin.
Question 5: What effect does cold water have on nitrogen narcosis during deep dives?
- Cold water eliminates narcosis entirely
- Cold water can worsen narcosis effects by reducing diver comfort and alertness (Correct answer)
- Cold water has no effect on narcosis
- Cold water delays the onset of narcosis
Correct answer: Cold water can worsen narcosis effects by reducing diver comfort and alertness
Cold water increases physiological stress and reduces alertness, which compounds the cognitive impairment effects of nitrogen narcosis.
Question 6: A dive plan calls for a maximum depth of 100 feet with a 20-minute bottom time. Which contingency plan is MOST important to include?
- A plan for mild currents
- An emergency ascent procedure if air runs low (Correct answer)
- A route for exploring the seafloor
- A schedule for underwater photography stops
Correct answer: An emergency ascent procedure if air runs low
Every deep dive plan must include an emergency ascent procedure specifying when and how to abort the dive if gas supplies drop critically.
Question 7: What does the term 'reverse dive profile' mean, and why is it generally discouraged for deep dives?
- Ascending before descending; it wastes bottom time
- Doing the deepest portion last in a series of dives; it can increase DCS risk (Correct answer)
- Starting a dive at low tide; it reduces visibility
- Diving without a buddy; it is prohibited by PADI
Correct answer: Doing the deepest portion last in a series of dives; it can increase DCS risk
A reverse dive profile, where the deepest dive comes last in a dive series, may increase decompression sickness risk due to residual nitrogen loading.
PADI Deep Diving Techniques & Planning 3
A diver notices their dive computer showing a flashing NDL warning at 80 feet.
What is the correct action?