DIVING CERTIFICATION
BSAC SPORTS DIVER THEORY QUESTIONS &
ANSWERS WITH GUARANTEED PASS!! 2026/2027
A+
Complete Blueprint Coverage
A+ 5 100%
QUESTIONS VERIFIED CORE DOMAINS COVERED RATIONALES INCLUDED
CATEGORIES
Physics of Diving & Gas Laws
Physiology & Dive Medicine
Equipment & Dive Planning
Dive Procedures, Safety & Emergency
Environment, Marine Life & BSAC Practices
STUVIAACTUALEXAM
, PHYSICS OF DIVING & GAS LAWS
Question 1
Q1. A Sports Diver is planning a dive to 30 metres in seawater. Using the approximate conversion that every 10 metres
of seawater equals 1 bar, the diver calculates absolute pressure at depth. What absolute pressure will the diver
experience at 30 metres, and why does this value matter for gas consumption planning?
A. 3 bar absolute; surface pressure is ignored when calculating cylinder endurance.
B. 4 bar absolute; the diver is under four times atmospheric pressure, so gas is consumed roughly four times faster than at
the surface.
C. 2 bar absolute; only the water column pressure is counted for SAC rate calculations.
D. 30 bar absolute; depth in metres is used directly as the pressure figure.
Correct Answer: B
Rationale:
Absolute pressure at 30 m is 4 bar (1 bar surface + 3 bar water). Gas density and consumption rate scale with absolute pressure, so
the diver will use gas approximately four times faster than at the surface. Option A understates pressure; C omits surface pressure; D
confuses depth with pressure units.
Question 2
Q2. During an ascent from 20 metres, a Sports Diver's buoyancy compensator is fully inflated and the diver begins to
accelerate toward the surface. Applying Boyle's law, what is the most immediate physical risk if the diver fails to vent the
BCD?
A. The BCD will lose volume and the diver will sink rapidly.
B. Expanding air in the BCD will increase buoyancy further, potentially causing an uncontrolled ascent and risk of pulmonary
barotrauma.
C. Nitrogen will come out of solution faster than the BCD can expand.
D. The cylinder pressure will drop suddenly due to the change in depth.
Correct Answer: B
Rationale:
Boyle's law states that gas volume increases as pressure decreases. Unvented BCD air expands on ascent, adding positive
buoyancy and accelerating the diver. This can lead to an uncontrolled ascent and lung over-expansion injury. Option A reverses the
volume change; C and D confuse unrelated physiological or equipment effects.
Question 3
Q3. A diver surfaces after a dive and notices that the contents gauge on the cylinder reads higher than the pressure
recorded at the end of the dive while still at depth. The water temperature was 8 °C and the surface air temperature is 22
°C. Which gas law primarily explains the observed pressure increase?
A. Boyle's law - volume change with pressure.
B. Charles' / Gay-Lussac's law - pressure rises with absolute temperature when volume is held constant.
C. Dalton's law - partial pressures of mixed gases.
D. Henry's law - gas solubility in liquids.
Correct Answer: B
Rationale:
With cylinder volume fixed, an increase in absolute temperature from cold water to warmer air raises the internal pressure according
to Gay-Lussac's (Charles') law. Boyle's law concerns volume-pressure at constant temperature; Dalton and Henry address partial
pressures and solubility, not temperature-driven pressure change in a closed cylinder.
, Question 4
Q4. A Sports Diver is breathing from a cylinder filled with air at 230 bar. At a depth of 30 metres the partial pressure of
nitrogen is calculated. Which value is correct and why is monitoring partial pressure important?
A. Approximately 0.79 bar; nitrogen partial pressure is independent of depth.
B. Approximately 3.16 bar; elevated nitrogen partial pressure increases the risk of nitrogen narcosis and contributes to
decompression obligation.
C. Approximately 1.0 bar; only oxygen partial pressure changes with depth.
D. Approximately 230 bar; total cylinder pressure equals nitrogen partial pressure.
Correct Answer: B
Rationale:
Air is ~79 % nitrogen. At 4 bar absolute the nitrogen partial pressure is 0.79 × 4 ≈ 3.16 bar. Raised PN2 is the primary driver of
narcosis and a major factor in decompression stress. Options A and C ignore the pressure multiplier; D confuses cylinder pressure
with partial pressure.
Question 5
Q5. While descending a shot line in clear water, a diver experiences increasing difficulty equalising the middle ears. The
dive leader signals to stop. From a physical standpoint, what is occurring inside the middle-ear space?
A. Middle-ear pressure is rising faster than ambient pressure, forcing the eardrum outward.
B. Ambient pressure is increasing while middle-ear volume is fixed, creating a relative vacuum that pulls the eardrum inward
until equalisation restores balance.
C. Nitrogen is rapidly dissolving into middle-ear tissues, reducing gas volume.
D. The Eustachian tube is actively pumping air out of the middle ear.
Correct Answer: B
Rationale:
On descent ambient pressure rises. If the Eustachian tube does not open, middle-ear pressure lags, producing a relative vacuum that
retracts the tympanic membrane. Equalisation introduces air to match ambient pressure. Option A reverses the pressure differential;
C and D misstate the mechanism.
Question 6
Q6. A diver plans to use a 12-litre cylinder filled to 230 bar for a dive with an expected surface air consumption of 20
litres per minute. At an average depth of 20 metres, approximately how long will the usable gas last if the diver reserves
50 bar for ascent and emergencies?
A. Approximately 54 minutes; depth has no effect on consumption rate.
B. Approximately 18 minutes; usable gas is (230 - 50) × 12 = 2160 litres, ambient pressure is 3 bar, so available
surface-equivalent gas is 720 litres, giving 36 minutes at 20 L/min SAC, but the calculation must still account for the average
pressure factor correctly yielding roughly 18-20 minutes of working time.
C. Approximately 108 minutes; the reserve is ignored in endurance calculations.
D. Approximately 9 minutes; the full 230 bar is treated as unavailable.
Correct Answer: B
Rationale:
Usable gas = (230 - 50) × 12 = 2160 litres. At 20 m (3 bar absolute) the effective surface-equivalent consumption is 20 × 3 = 60 L/min,
so endurance ≈ = 36 minutes of total gas time; practical working time is typically shorter once ascent and safety margins are
considered, but the physics correctly scales consumption by absolute pressure. Option A ignores depth; C and D misapply the
reserve or total pressure.
BSAC SPORTS DIVER THEORY QUESTIONS &
ANSWERS WITH GUARANTEED PASS!! 2026/2027
A+
Complete Blueprint Coverage
A+ 5 100%
QUESTIONS VERIFIED CORE DOMAINS COVERED RATIONALES INCLUDED
CATEGORIES
Physics of Diving & Gas Laws
Physiology & Dive Medicine
Equipment & Dive Planning
Dive Procedures, Safety & Emergency
Environment, Marine Life & BSAC Practices
STUVIAACTUALEXAM
, PHYSICS OF DIVING & GAS LAWS
Question 1
Q1. A Sports Diver is planning a dive to 30 metres in seawater. Using the approximate conversion that every 10 metres
of seawater equals 1 bar, the diver calculates absolute pressure at depth. What absolute pressure will the diver
experience at 30 metres, and why does this value matter for gas consumption planning?
A. 3 bar absolute; surface pressure is ignored when calculating cylinder endurance.
B. 4 bar absolute; the diver is under four times atmospheric pressure, so gas is consumed roughly four times faster than at
the surface.
C. 2 bar absolute; only the water column pressure is counted for SAC rate calculations.
D. 30 bar absolute; depth in metres is used directly as the pressure figure.
Correct Answer: B
Rationale:
Absolute pressure at 30 m is 4 bar (1 bar surface + 3 bar water). Gas density and consumption rate scale with absolute pressure, so
the diver will use gas approximately four times faster than at the surface. Option A understates pressure; C omits surface pressure; D
confuses depth with pressure units.
Question 2
Q2. During an ascent from 20 metres, a Sports Diver's buoyancy compensator is fully inflated and the diver begins to
accelerate toward the surface. Applying Boyle's law, what is the most immediate physical risk if the diver fails to vent the
BCD?
A. The BCD will lose volume and the diver will sink rapidly.
B. Expanding air in the BCD will increase buoyancy further, potentially causing an uncontrolled ascent and risk of pulmonary
barotrauma.
C. Nitrogen will come out of solution faster than the BCD can expand.
D. The cylinder pressure will drop suddenly due to the change in depth.
Correct Answer: B
Rationale:
Boyle's law states that gas volume increases as pressure decreases. Unvented BCD air expands on ascent, adding positive
buoyancy and accelerating the diver. This can lead to an uncontrolled ascent and lung over-expansion injury. Option A reverses the
volume change; C and D confuse unrelated physiological or equipment effects.
Question 3
Q3. A diver surfaces after a dive and notices that the contents gauge on the cylinder reads higher than the pressure
recorded at the end of the dive while still at depth. The water temperature was 8 °C and the surface air temperature is 22
°C. Which gas law primarily explains the observed pressure increase?
A. Boyle's law - volume change with pressure.
B. Charles' / Gay-Lussac's law - pressure rises with absolute temperature when volume is held constant.
C. Dalton's law - partial pressures of mixed gases.
D. Henry's law - gas solubility in liquids.
Correct Answer: B
Rationale:
With cylinder volume fixed, an increase in absolute temperature from cold water to warmer air raises the internal pressure according
to Gay-Lussac's (Charles') law. Boyle's law concerns volume-pressure at constant temperature; Dalton and Henry address partial
pressures and solubility, not temperature-driven pressure change in a closed cylinder.
, Question 4
Q4. A Sports Diver is breathing from a cylinder filled with air at 230 bar. At a depth of 30 metres the partial pressure of
nitrogen is calculated. Which value is correct and why is monitoring partial pressure important?
A. Approximately 0.79 bar; nitrogen partial pressure is independent of depth.
B. Approximately 3.16 bar; elevated nitrogen partial pressure increases the risk of nitrogen narcosis and contributes to
decompression obligation.
C. Approximately 1.0 bar; only oxygen partial pressure changes with depth.
D. Approximately 230 bar; total cylinder pressure equals nitrogen partial pressure.
Correct Answer: B
Rationale:
Air is ~79 % nitrogen. At 4 bar absolute the nitrogen partial pressure is 0.79 × 4 ≈ 3.16 bar. Raised PN2 is the primary driver of
narcosis and a major factor in decompression stress. Options A and C ignore the pressure multiplier; D confuses cylinder pressure
with partial pressure.
Question 5
Q5. While descending a shot line in clear water, a diver experiences increasing difficulty equalising the middle ears. The
dive leader signals to stop. From a physical standpoint, what is occurring inside the middle-ear space?
A. Middle-ear pressure is rising faster than ambient pressure, forcing the eardrum outward.
B. Ambient pressure is increasing while middle-ear volume is fixed, creating a relative vacuum that pulls the eardrum inward
until equalisation restores balance.
C. Nitrogen is rapidly dissolving into middle-ear tissues, reducing gas volume.
D. The Eustachian tube is actively pumping air out of the middle ear.
Correct Answer: B
Rationale:
On descent ambient pressure rises. If the Eustachian tube does not open, middle-ear pressure lags, producing a relative vacuum that
retracts the tympanic membrane. Equalisation introduces air to match ambient pressure. Option A reverses the pressure differential;
C and D misstate the mechanism.
Question 6
Q6. A diver plans to use a 12-litre cylinder filled to 230 bar for a dive with an expected surface air consumption of 20
litres per minute. At an average depth of 20 metres, approximately how long will the usable gas last if the diver reserves
50 bar for ascent and emergencies?
A. Approximately 54 minutes; depth has no effect on consumption rate.
B. Approximately 18 minutes; usable gas is (230 - 50) × 12 = 2160 litres, ambient pressure is 3 bar, so available
surface-equivalent gas is 720 litres, giving 36 minutes at 20 L/min SAC, but the calculation must still account for the average
pressure factor correctly yielding roughly 18-20 minutes of working time.
C. Approximately 108 minutes; the reserve is ignored in endurance calculations.
D. Approximately 9 minutes; the full 230 bar is treated as unavailable.
Correct Answer: B
Rationale:
Usable gas = (230 - 50) × 12 = 2160 litres. At 20 m (3 bar absolute) the effective surface-equivalent consumption is 20 × 3 = 60 L/min,
so endurance ≈ = 36 minutes of total gas time; practical working time is typically shorter once ascent and safety margins are
considered, but the physics correctly scales consumption by absolute pressure. Option A ignores depth; C and D misapply the
reserve or total pressure.
