PADI Open Water Final Exams A and B |
2025/2026 Edition | Package Deal – Answers |
Verified and Updated | Open Water Diver
Certification
Section 1: Dive Physics and Physiology (Q1–Q30)
1. According to Boyle's Law, what happens to the volume of air in a flexible air space as a
diver descends?
A. It increases as pressure increases
B. It decreases as pressure increases
C. It remains unchanged at all depths
D. It disappears completely at 10 meters
Answer: B
Rationale: Boyle's Law states that gas volume varies inversely with pressure, so air spaces
compress during descent.
2. At what depth does a diver experience 2 ATA of pressure in seawater?
A. 5 meters (16 feet)
B. 10 meters (33 feet)
C. 20 meters (66 feet)
D. 30 meters (100 feet)
Answer: B
Rationale: Pressure increases by 1 ATA for every 10 meters (33 feet) of seawater depth. At 10
meters, the ambient pressure is 2 ATA.
3. A diver takes 6 liters of air from the surface to 20 meters (66 feet). What will the volume be
at depth?
A. 6 liters
B. 3 liters
C. 2 liters
D. 1 liter
Answer: C
Rationale: At 20 meters, pressure is 3 ATA. Volume is inversely proportional to pressure, so 6
liters ÷ 3 = 2 liters.
4. Why must a diver equalize air spaces early and often during descent?
A. Equalizing reduces nitrogen absorption to zero
,B. Increasing pressure compresses air spaces and can cause squeeze
C. Equalizing makes the tank last longer
D. Equalizing replaces the need for buoyancy control
Answer: B
Rationale: As pressure rises during descent, air spaces in the ears, mask, and sinuses compress
unless air is added to equalize pressure, preventing barotrauma.
5. What is a squeeze?
A. A pressure imbalance between the surrounding pressure and an air space
B. Too much air in a body air space
C. Rapid ascent
D. Holding your breath
Answer: A
Rationale: A squeeze occurs when there is a pressure imbalance between the surrounding
water pressure and the air space in a body cavity or equipment.
6. Equalization is the process of:
A. Removing air from an air space
B. Adding air to an air space
C. Descending rapidly
D. Holding your breath
Answer: B
Rationale: Equalization is the process of adding air to an air space to balance the pressure
inside with the surrounding water pressure.
7. During ascent, a diver feels discomfort in their ears. What should they do?
A. Continue ascending quickly
B. Stop, descend slightly, and allow trapped air to work its way out
C. Hold their breath and push harder
D. Ignore the discomfort
Answer: B
Rationale: If ear discomfort occurs during ascent, the diver should stop, descend slightly, and
allow trapped air to escape. This prevents barotrauma.
8. What is the most important rule in scuba diving?
A. Always dive with a buddy
B. Breathe continuously and never hold your breath
C. Ascend slowly
D. Equalize early and often
,Answer: B
Rationale: Breathing continuously and never holding your breath is the most critical rule in
scuba diving to prevent lung overexpansion injuries.
9. While ascending, a diver holds their breath. What is the most likely consequence?
A. Decompression sickness
B. Nitrogen narcosis
C. Lung overexpansion injury
D. Shallow water blackout
Answer: C
Rationale: According to Boyle's Law, air expands as pressure decreases during ascent. If a diver
holds their breath, expanding air can rupture lung tissue, leading to lung overexpansion injury.
10. A balloon fully inflated and sealed at 10 meters (33 feet) would probably _______ during
ascent to the surface.
A. Shrink
B. Remain the same
C. Burst
D. Fill with water
Answer: C
Rationale: As the balloon ascends, pressure decreases and the air inside expands. A balloon
sealed at depth will likely burst during ascent.
11. What is the pressure change for each 10 meters (33 feet) of depth change in seawater?
A. 0.5 atmospheres
B. 1 atmosphere
C. 2 atmospheres
D. 3 atmospheres
Answer: B
Rationale: Pressure increases by 1 atmosphere (ATA) for every 10 meters (33 feet) of seawater
depth.
12. A diver at 12 meters (40 feet) would expect to use air _______ at 6 meters (20 feet).
A. Faster than
B. Slower than
C. At the same rate as
D. Not at all
Answer: A
Rationale: At greater depth, air is denser and the diver uses air faster. At 12 meters (2.2 ATA),
air consumption is higher than at 6 meters (1.6 ATA).
, 13. The most efficient way to breathe dense air underwater is to breathe:
A. Shallowly and rapidly
B. Deeply and slowly
C. Normally
D. Through the nose only
Answer: B
Rationale: Breathing deeply and slowly maximizes gas exchange and reduces air consumption
when breathing dense air underwater.
14. Buoyancy is defined as:
A. A force that pushes an object in water upward
B. A force that pulls an object downward
C. The weight of an object in water
D. The density of water
Answer: A
Rationale: Buoyancy is the upward force exerted by water on an object, determined by the
weight of water displaced (Archimedes' Principle).
15. Salt water causes more buoyancy than fresh water because it is _______ dense and
weighs _______.
A. Less, less
B. More, more
C. More, less
D. Less, more
Answer: B
Rationale: Salt water is denser and weighs more than fresh water, providing greater buoyancy.
16. When descending, buoyancy tends to _______; when ascending, it tends to _______.
A. Increase, decrease
B. Decrease, increase
C. Remain the same, remain the same
D. Decrease, decrease
Answer: B
Rationale: During descent, air in the BCD and wetsuit compresses, decreasing buoyancy. During
ascent, air expands, increasing buoyancy.
17. According to Henry's Law, gas dissolves in a liquid in proportion to:
A. The temperature of the liquid
B. The partial pressure of the gas
C. The volume of the liquid
D. The density of the liquid
2025/2026 Edition | Package Deal – Answers |
Verified and Updated | Open Water Diver
Certification
Section 1: Dive Physics and Physiology (Q1–Q30)
1. According to Boyle's Law, what happens to the volume of air in a flexible air space as a
diver descends?
A. It increases as pressure increases
B. It decreases as pressure increases
C. It remains unchanged at all depths
D. It disappears completely at 10 meters
Answer: B
Rationale: Boyle's Law states that gas volume varies inversely with pressure, so air spaces
compress during descent.
2. At what depth does a diver experience 2 ATA of pressure in seawater?
A. 5 meters (16 feet)
B. 10 meters (33 feet)
C. 20 meters (66 feet)
D. 30 meters (100 feet)
Answer: B
Rationale: Pressure increases by 1 ATA for every 10 meters (33 feet) of seawater depth. At 10
meters, the ambient pressure is 2 ATA.
3. A diver takes 6 liters of air from the surface to 20 meters (66 feet). What will the volume be
at depth?
A. 6 liters
B. 3 liters
C. 2 liters
D. 1 liter
Answer: C
Rationale: At 20 meters, pressure is 3 ATA. Volume is inversely proportional to pressure, so 6
liters ÷ 3 = 2 liters.
4. Why must a diver equalize air spaces early and often during descent?
A. Equalizing reduces nitrogen absorption to zero
,B. Increasing pressure compresses air spaces and can cause squeeze
C. Equalizing makes the tank last longer
D. Equalizing replaces the need for buoyancy control
Answer: B
Rationale: As pressure rises during descent, air spaces in the ears, mask, and sinuses compress
unless air is added to equalize pressure, preventing barotrauma.
5. What is a squeeze?
A. A pressure imbalance between the surrounding pressure and an air space
B. Too much air in a body air space
C. Rapid ascent
D. Holding your breath
Answer: A
Rationale: A squeeze occurs when there is a pressure imbalance between the surrounding
water pressure and the air space in a body cavity or equipment.
6. Equalization is the process of:
A. Removing air from an air space
B. Adding air to an air space
C. Descending rapidly
D. Holding your breath
Answer: B
Rationale: Equalization is the process of adding air to an air space to balance the pressure
inside with the surrounding water pressure.
7. During ascent, a diver feels discomfort in their ears. What should they do?
A. Continue ascending quickly
B. Stop, descend slightly, and allow trapped air to work its way out
C. Hold their breath and push harder
D. Ignore the discomfort
Answer: B
Rationale: If ear discomfort occurs during ascent, the diver should stop, descend slightly, and
allow trapped air to escape. This prevents barotrauma.
8. What is the most important rule in scuba diving?
A. Always dive with a buddy
B. Breathe continuously and never hold your breath
C. Ascend slowly
D. Equalize early and often
,Answer: B
Rationale: Breathing continuously and never holding your breath is the most critical rule in
scuba diving to prevent lung overexpansion injuries.
9. While ascending, a diver holds their breath. What is the most likely consequence?
A. Decompression sickness
B. Nitrogen narcosis
C. Lung overexpansion injury
D. Shallow water blackout
Answer: C
Rationale: According to Boyle's Law, air expands as pressure decreases during ascent. If a diver
holds their breath, expanding air can rupture lung tissue, leading to lung overexpansion injury.
10. A balloon fully inflated and sealed at 10 meters (33 feet) would probably _______ during
ascent to the surface.
A. Shrink
B. Remain the same
C. Burst
D. Fill with water
Answer: C
Rationale: As the balloon ascends, pressure decreases and the air inside expands. A balloon
sealed at depth will likely burst during ascent.
11. What is the pressure change for each 10 meters (33 feet) of depth change in seawater?
A. 0.5 atmospheres
B. 1 atmosphere
C. 2 atmospheres
D. 3 atmospheres
Answer: B
Rationale: Pressure increases by 1 atmosphere (ATA) for every 10 meters (33 feet) of seawater
depth.
12. A diver at 12 meters (40 feet) would expect to use air _______ at 6 meters (20 feet).
A. Faster than
B. Slower than
C. At the same rate as
D. Not at all
Answer: A
Rationale: At greater depth, air is denser and the diver uses air faster. At 12 meters (2.2 ATA),
air consumption is higher than at 6 meters (1.6 ATA).
, 13. The most efficient way to breathe dense air underwater is to breathe:
A. Shallowly and rapidly
B. Deeply and slowly
C. Normally
D. Through the nose only
Answer: B
Rationale: Breathing deeply and slowly maximizes gas exchange and reduces air consumption
when breathing dense air underwater.
14. Buoyancy is defined as:
A. A force that pushes an object in water upward
B. A force that pulls an object downward
C. The weight of an object in water
D. The density of water
Answer: A
Rationale: Buoyancy is the upward force exerted by water on an object, determined by the
weight of water displaced (Archimedes' Principle).
15. Salt water causes more buoyancy than fresh water because it is _______ dense and
weighs _______.
A. Less, less
B. More, more
C. More, less
D. Less, more
Answer: B
Rationale: Salt water is denser and weighs more than fresh water, providing greater buoyancy.
16. When descending, buoyancy tends to _______; when ascending, it tends to _______.
A. Increase, decrease
B. Decrease, increase
C. Remain the same, remain the same
D. Decrease, decrease
Answer: B
Rationale: During descent, air in the BCD and wetsuit compresses, decreasing buoyancy. During
ascent, air expands, increasing buoyancy.
17. According to Henry's Law, gas dissolves in a liquid in proportion to:
A. The temperature of the liquid
B. The partial pressure of the gas
C. The volume of the liquid
D. The density of the liquid
