BSAC Sports Diver Theory Exam Actual
Exam 2026/2027 – 100% Verified
Questions with Answers – Pass
Guaranteed – A+ Graded
SECTION 1: DIVE PHYSICS
SCENARIO: Physics - Pressure and Depth
A diver descends to 30 meters in seawater. The ambient pressure at this depth is 4 bar absolute
(1 bar surface + 3 bar from depth). A flexible container with 3 litres of air at the surface is taken
to this depth.
Q1: What will be the approximate volume of the air in the flexible container at 30 meters,
assuming constant temperature?
A. 1.0 litres
B. 0.75 litres
C. 0.5 litres [CORRECT]
D. 0.25 litres
Correct Answer: C
Rationale: Boyle's Law states that at constant temperature, the volume of a gas is inversely
proportional to pressure (P₁V₁ = P₂V₂). At surface (1 bar), V₁ = 3 litres. At 30m (4 bar absolute), V₂
= (P₁ × V₁)/P₂ = (1 × 3)/4 = 0.75 litres. Option C is correct. Boyle's Law is fundamental to
understanding gas behaviour in diving, affecting BCD function, lung volume, and air
consumption.
Q2: A diver's cylinder contains 200 bar of air at 10°C. If the cylinder is left in direct sunlight and
warms to 30°C, what will happen to the cylinder pressure (assuming constant volume)?
A. Decrease to approximately 180 bar
B. Increase to approximately 215 bar [CORRECT]
C. Remain unchanged at 200 bar
D. Decrease to approximately 190 bar
,Correct Answer: B
Rationale: Charles's Law states that at constant volume, the pressure of a gas is directly
proportional to its absolute temperature. Using P₁/T₁ = P₂/T₂, T₁ = 283K (10°C + 273), T₂ = 303K
(30°C + 273). P₂ = 200 × (303/283) = 214.1 bar. This demonstrates the importance of keeping
cylinders cool and checking pressure after temperature changes.
Q3: A diver breathes air at 40 meters depth. What is the partial pressure of nitrogen (PN₂) in the
breathing gas at this depth, assuming air is 79% nitrogen?
A. 1.58 bar
B. 2.37 bar
C. 3.95 bar [CORRECT]
D. 4.74 bar
Correct Answer: C
Rationale: Dalton's Law states that total pressure is the sum of partial pressures of individual
gases. At 40 meters, total absolute pressure = 5 bar (1 bar surface + 4 bar water pressure). PN₂ =
5 bar × 0.79 = 3.95 bar. This explains why nitrogen narcosis becomes significant at depth and
why nitrox has lower nitrogen partial pressures for a given depth.
SCENARIO: Physics - Buoyancy and Archimedes' Principle
A diver weighs 80 kg with full equipment. The total volume of the diver and equipment is 78
litres of seawater (density 1.025 kg/l). The diver is currently neutrally buoyant.
Q4: What is the total weight of seawater displaced by the diver?
A. 76.1 kg
B. 78.0 kg
C. 79.95 kg [CORRECT]
D. 82.0 kg
Correct Answer: C
Rationale: Archimedes' Principle states that the buoyant force equals the weight of the
displaced fluid. Volume displaced = 78 litres. Weight of displaced seawater = 78 L × 1.025 kg/L =
79.95 kg. For neutral buoyancy, the diver's weight (80 kg) would need to be adjusted by
adding/removing weights to equal 79.95 kg. This principle is essential for proper weighting.
, Q5: If the diver descends to 20 meters and the BCD volume is reduced by 1 litre (compressed
air), what happens to the diver's buoyancy?
A. Becomes more positively buoyant
B. Becomes more negatively buoyant [CORRECT]
C. Remains neutrally buoyant
D. Becomes positively buoyant by 0.5 kg
Correct Answer: B
Rationale: As the diver descends, the air in the BCD compresses (Boyle's Law), reducing
displacement volume. With less volume displaced, buoyant force decreases and the diver
becomes more negatively buoyant. This is why divers must add air to their BCD during descent
to maintain neutral buoyancy.
Q6: Which colour of light is absorbed FIRST as a diver descends through the water column?
A. Blue
B. Green
C. Red [CORRECT]
D. Yellow
Correct Answer: C
Rationale: Red light is absorbed first in water because it has the longest wavelength and lowest
energy in the visible spectrum. Water molecules absorb longer wavelengths preferentially. Blue
light penetrates deepest. This explains why colours appear different underwater and why dive
lights are important for colour perception.
Q7: A sound signal is produced underwater. How does the speed of sound in water compare to
its speed in air?
A. 2 times slower
B. 4 times faster [CORRECT]
C. 10 times slower
D. Approximately the same speed
Correct Answer: B
Rationale: Sound travels approximately four times faster in water (approximately 1,500 m/s)
than in air (approximately 340 m/s) because water is denser and more incompressible. This
affects how divers perceive sounds, locate direction, and communicate underwater.
Exam 2026/2027 – 100% Verified
Questions with Answers – Pass
Guaranteed – A+ Graded
SECTION 1: DIVE PHYSICS
SCENARIO: Physics - Pressure and Depth
A diver descends to 30 meters in seawater. The ambient pressure at this depth is 4 bar absolute
(1 bar surface + 3 bar from depth). A flexible container with 3 litres of air at the surface is taken
to this depth.
Q1: What will be the approximate volume of the air in the flexible container at 30 meters,
assuming constant temperature?
A. 1.0 litres
B. 0.75 litres
C. 0.5 litres [CORRECT]
D. 0.25 litres
Correct Answer: C
Rationale: Boyle's Law states that at constant temperature, the volume of a gas is inversely
proportional to pressure (P₁V₁ = P₂V₂). At surface (1 bar), V₁ = 3 litres. At 30m (4 bar absolute), V₂
= (P₁ × V₁)/P₂ = (1 × 3)/4 = 0.75 litres. Option C is correct. Boyle's Law is fundamental to
understanding gas behaviour in diving, affecting BCD function, lung volume, and air
consumption.
Q2: A diver's cylinder contains 200 bar of air at 10°C. If the cylinder is left in direct sunlight and
warms to 30°C, what will happen to the cylinder pressure (assuming constant volume)?
A. Decrease to approximately 180 bar
B. Increase to approximately 215 bar [CORRECT]
C. Remain unchanged at 200 bar
D. Decrease to approximately 190 bar
,Correct Answer: B
Rationale: Charles's Law states that at constant volume, the pressure of a gas is directly
proportional to its absolute temperature. Using P₁/T₁ = P₂/T₂, T₁ = 283K (10°C + 273), T₂ = 303K
(30°C + 273). P₂ = 200 × (303/283) = 214.1 bar. This demonstrates the importance of keeping
cylinders cool and checking pressure after temperature changes.
Q3: A diver breathes air at 40 meters depth. What is the partial pressure of nitrogen (PN₂) in the
breathing gas at this depth, assuming air is 79% nitrogen?
A. 1.58 bar
B. 2.37 bar
C. 3.95 bar [CORRECT]
D. 4.74 bar
Correct Answer: C
Rationale: Dalton's Law states that total pressure is the sum of partial pressures of individual
gases. At 40 meters, total absolute pressure = 5 bar (1 bar surface + 4 bar water pressure). PN₂ =
5 bar × 0.79 = 3.95 bar. This explains why nitrogen narcosis becomes significant at depth and
why nitrox has lower nitrogen partial pressures for a given depth.
SCENARIO: Physics - Buoyancy and Archimedes' Principle
A diver weighs 80 kg with full equipment. The total volume of the diver and equipment is 78
litres of seawater (density 1.025 kg/l). The diver is currently neutrally buoyant.
Q4: What is the total weight of seawater displaced by the diver?
A. 76.1 kg
B. 78.0 kg
C. 79.95 kg [CORRECT]
D. 82.0 kg
Correct Answer: C
Rationale: Archimedes' Principle states that the buoyant force equals the weight of the
displaced fluid. Volume displaced = 78 litres. Weight of displaced seawater = 78 L × 1.025 kg/L =
79.95 kg. For neutral buoyancy, the diver's weight (80 kg) would need to be adjusted by
adding/removing weights to equal 79.95 kg. This principle is essential for proper weighting.
, Q5: If the diver descends to 20 meters and the BCD volume is reduced by 1 litre (compressed
air), what happens to the diver's buoyancy?
A. Becomes more positively buoyant
B. Becomes more negatively buoyant [CORRECT]
C. Remains neutrally buoyant
D. Becomes positively buoyant by 0.5 kg
Correct Answer: B
Rationale: As the diver descends, the air in the BCD compresses (Boyle's Law), reducing
displacement volume. With less volume displaced, buoyant force decreases and the diver
becomes more negatively buoyant. This is why divers must add air to their BCD during descent
to maintain neutral buoyancy.
Q6: Which colour of light is absorbed FIRST as a diver descends through the water column?
A. Blue
B. Green
C. Red [CORRECT]
D. Yellow
Correct Answer: C
Rationale: Red light is absorbed first in water because it has the longest wavelength and lowest
energy in the visible spectrum. Water molecules absorb longer wavelengths preferentially. Blue
light penetrates deepest. This explains why colours appear different underwater and why dive
lights are important for colour perception.
Q7: A sound signal is produced underwater. How does the speed of sound in water compare to
its speed in air?
A. 2 times slower
B. 4 times faster [CORRECT]
C. 10 times slower
D. Approximately the same speed
Correct Answer: B
Rationale: Sound travels approximately four times faster in water (approximately 1,500 m/s)
than in air (approximately 340 m/s) because water is denser and more incompressible. This
affects how divers perceive sounds, locate direction, and communicate underwater.
