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1
Q

What is buoyancy?

A

The force that supports an object in a liquid, allowing it to float, sink, or remain neutrally buoyant.

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2
Q

What is neutral buoyancy?

A

When an object neither sinks nor floats, achieved by balancing weight and buoyancy (e.g., using a BCD).

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3
Q

How does pressure increase with depth in water?

A

Pressure increases by 1 atmosphere (ata) for every 10 meters/33 feet of seawater.

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4
Q

What is the absolute pressure at 10 meters/33 feet in seawater?

A

2 ata (1 ata from air + 1 ata from 10 meters of water).

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5
Q

How does Boyle’s Law apply to diving?

A

As pressure increases with depth, gas volume decreases; as pressure decreases, gas volume increases.

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6
Q

Why must divers ascend slowly?

A

To allow expanding gases in the lungs to escape safely, preventing lung overexpansion injuries.

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7
Q

What is the relationship between pressure and gas density?

A

As pressure increases with depth, gas density increases, making air thicker to breathe.

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8
Q

What is a squeeze in diving?

A

Pain or discomfort caused by pressure imbalance in air spaces (e.g., ears, sinuses) during descent.

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9
Q

How do you equalize your ears during descent?

A

Pinch your nose and gently blow (Valsalva maneuver) or swallow (Toynbee maneuver) to open Eustachian tubes.

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10
Q

What happens to colors underwater?

A

Colors are absorbed by water; red disappears first, followed by orange, yellow, etc., with increasing depth.

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11
Q

Why do objects appear larger underwater?

A

Light refracts in water, magnifying objects by about one-third.

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12
Q

How does water affect sound underwater?

A

Sound travels four times faster in water than in air, making it harder to locate the source.

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13
Q

What is the formula for calculating absolute pressure in diving?

A

Absolute pressure (ata) = depth (meters) / 10 + 1 (or depth (feet) / 33 + 1).

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14
Q

What is the partial pressure of oxygen at sea level (1 ata)?

A

Approximately 0.21 ata (21% of 1 ata).

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15
Q

Why is nitrogen narcosis a concern at depth?

A

Increased pressure causes nitrogen to affect the nervous system, impairing judgment (like drunkenness).

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16
Q

What is the volume of a balloon at 20 meters if it was 10 liters at the surface?

A

3.33 liters (Boyle’s Law: 10 liters / (20m / 10 + 1) = 10 / 3).

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17
Q

What is Dalton’s Law in diving?

A

The total pressure of a gas mixture is the sum of the partial pressures of its component gases.

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18
Q

Why do divers feel less weight underwater?

A

Buoyancy counteracts gravity, making objects feel lighter.

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19
Q

What is Archimedes’ Principle?

A

An object in a fluid is buoyed up by a force equal to the weight of the fluid displaced.

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20
Q

How does temperature affect diving?

A

Water conducts heat 20 times faster than air, increasing the risk of hypothermia.

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21
Q

What is decompression sickness (DCS)?

A

A condition caused by nitrogen bubbles forming in the body due to rapid ascent.

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22
Q

What are symptoms of decompression sickness?

A

Joint pain, fatigue, dizziness, rash, or neurological issues (e.g., numbness, paralysis).

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23
Q

How can divers prevent decompression sickness?

A

Ascend slowly, perform safety stops, and follow dive tables or computers.

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24
Q

What is a safety stop, and when is it performed?

A

A 3–5 minute pause at 5 meters/15 feet to allow nitrogen off-gassing.

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25
What is nitrogen narcosis?
Impaired mental function due to nitrogen under pressure, typically below 30 meters/100 feet.
26
What is the “martini rule” for nitrogen narcosis?
Every 10 meters/33 feet below 20 meters feels like one martini (e.g., 30m = 1 martini).
27
What is an arterial gas embolism (AGE)?
Gas bubbles entering the bloodstream due to lung overexpansion, potentially causing stroke-like symptoms.
28
What causes lung overexpansion injuries?
Holding your breath during ascent, causing air in the lungs to expand.
29
How do you prevent lung overexpansion injuries?
Breathe continuously and ascend slowly (no faster than 18m/60ft per minute).
30
What is oxygen toxicity in diving?
Excessive oxygen partial pressure (usually >1.4 ata) causing convulsions or other symptoms.
31
What is the maximum depth for recreational diving on air to avoid oxygen toxicity?
56 meters/184 feet (where oxygen partial pressure reaches 1.4 ata).
32
What is a reverse squeeze?
Pain in air spaces (e.g., ears) during ascent due to trapped gas; solved by descending slightly.
33
Why do divers get dehydrated?
Breathing dry tank air and immersion diuresis (pressure-induced urination) increase fluid loss.
34
What is the effect of cold water on divers?
Increases risk of hypothermia and reduces dexterity, affecting equipment handling.
35
What is the purpose of a dive computer?
Tracks depth, time, and nitrogen absorption to prevent decompression sickness.
36
What is the no-decompression limit (NDL)?
The maximum time a diver can stay at a depth without requiring decompression stops.
37
What happens if you exceed the no-decompression limit?
You may need decompression stops to safely off-gas nitrogen, or risk DCS.
38
What is a repetitive dive?
A dive conducted within 6–24 hours of a previous dive, with residual nitrogen in the body.
39
How does altitude affect diving?
Lower atmospheric pressure at altitude reduces safe dive times; use altitude dive tables.
40
What is the role of the diaphragm in breathing?
The muscle that contracts to draw air into the lungs; divers must breathe deeply using it.
41
What is a BCD (Buoyancy Control Device)?
An inflatable vest used to control buoyancy by adding or releasing air.
42
What are the main components of a scuba regulator?
First stage (attaches to tank), second stage (mouthpiece), alternate air source, and gauges.
43
What does the SPG (submersible pressure gauge) do?
Displays the remaining air pressure in the tank.
44
What is the purpose of a dive mask?
Creates an air space to allow clear vision underwater and protects the eyes.
45
How do you clear a flooded mask underwater?
Tilt head back, press the top of the mask, and exhale through your nose.
46
What is the role of fins in diving?
Increase swimming efficiency and reduce energy use; types include open-heel and full-foot.
47
What is a snorkel used for in scuba diving?
Allows breathing at the surface without using tank air, conserving gas.
48
What is a weight system?
Lead weights used to counteract buoyancy, allowing divers to sink.
49
How do you check your weight system before a dive?
Ensure weights are secure and quick-release mechanisms work properly.
50
What is a dive computer, and why is it important?
Tracks depth, time, and nitrogen levels to ensure safe dive profiles.
51
What is the purpose of a tank boot?
Protects the tank base and prevents it from rolling on a boat.
52
What is a low-pressure inflator hose?
Connects the BCD to the regulator to add air for buoyancy control.
53
Why do divers wear exposure suits?
To protect against cold, sunburn, abrasions, and marine life stings.
54
What is the difference between a wetsuit and a drysuit?
Wetsuits insulate with a thin layer of water; drysuits keep you dry and insulate with air.
55
What is a dive knife used for?
To cut fishing lines, nets, or other entanglements, not as a weapon.
56
How often should scuba equipment be serviced?
Annually or per manufacturer guidelines, plus visual inspections before dives.
57
What is an O-ring in scuba equipment?
A rubber seal in the tank valve or regulator to prevent air leaks.
58
What should you do if your regulator free-flows?
Breathe lightly from it while ascending; use alternate air source if needed.
59
What is a surface marker buoy (SMB)?
An inflatable device to signal your position to the boat or surface.
60
How do you perform a pre-dive equipment check (BWRAF)?
Buoyancy, Weights, Releases, Air, Final OK—check BCD, weights, quick releases, air supply, and gear.
61
What is the buddy system in diving?
Diving with a partner for safety, mutual assistance, and emergency response.
62
What is the most important rule in scuba diving?
Never hold your breath; breathe continuously to avoid lung injuries.
63
What is the recommended ascent rate for divers?
No faster than 18 meters/60 feet per minute (or follow dive computer).
64
How do you perform a controlled emergency swimming ascent (CESA)?
Swim to the surface while exhaling continuously, keeping the regulator in your mouth.
65
What is the hand signal for 'OK'?
Form a circle with thumb and index finger, other fingers extended.
66
What is the hand signal for 'Problem' or 'Something’s wrong'?
Hand flat, palm down, tilting side to side.
67
How do you share air with a buddy?
Offer your alternate air source (octopus) or use their alternate air source.
68
What should you do if you run out of air?
Signal your buddy, share air, and ascend together safely.
69
What is the purpose of a pre-dive safety check?
To ensure all equipment is functioning and both divers are ready.
70
What is a giant stride entry?
A method of entering deep water by stepping off a platform with a large step, regulator in mouth.
71
How do you perform a back roll entry?
Sit on the edge of a boat, hold your mask and regulator, and roll backward into the water.
72
What is the purpose of a dive plan?
To outline depth, time, air management, and emergency procedures for a safe dive.
73
What is the minimum air pressure to surface safely?
50 bar/500 psi to ensure enough air for ascent and safety stop.
74
How do you clear a regulator underwater?
Exhale sharply or press the purge button to remove water.
75
What is a buddy check, and when is it done?
A pre-dive inspection of each other’s gear, done before entering the water.
76
What should you do if you get separated from your buddy?
Search for one minute (360-degree turn), then ascend to the surface.
77
What is the hand signal for 'Low on air'?
Hand flat across the throat or pointing to the SPG.
78
How do you control buoyancy during a dive?
Adjust air in the BCD and use proper breathing (inhale to rise, exhale to descend).
79
What is a safety stop, and why is it important?
A stop at 5 meters/15 feet to allow nitrogen off-gassing and reduce DCS risk.
80
What should a diver do after searching for one minute?
Ascend to the surface ## Footnote A complete 360-degree turn is recommended during the search.
81
What is the hand signal for 'Low on air'?
Hand flat across the throat or pointing to the SPG
82
How do you control buoyancy during a dive?
Adjust air in the BCD and use proper breathing: inhale to rise, exhale to descend
83
What is a safety stop, and why is it important?
A pause at 5 meters/15 feet for 3–5 minutes to off-gas nitrogen and reduce DCS risk
84
What should you do if you feel a reverse block in your ears?
Descend slightly to relieve pressure, then ascend slowly
85
What is the hand signal for 'Ascend'?
Thumb pointing upward
86
What is the hand signal for 'Descend'?
Thumb pointing downward
87
How do you perform a weight belt removal underwater?
Unbuckle the belt, hold it away from your body, and drop it if necessary
88
What is the purpose of a dive flag?
Alerts boats to divers in the area to avoid collisions
89
What should you do if caught in a current?
Swim across the current to shore or signal for help; don’t fight it directly
90
What is the procedure for an out-of-air emergency?
Signal buddy, share air, ascend together slowly with a safety stop if possible
91
How do you prevent mask fogging?
Apply defog solution (e.g., spit or commercial spray) before the dive
92
What is the hand signal for 'Stop'?
Hand flat, palm facing forward
93
What should you do if you see marine life acting aggressively?
Stay calm, maintain distance, and slowly back away without sudden movements
94
How do you log a dive?
Record depth, time, location, air used, and notable observations in a dive logbook
95
Why should divers avoid touching coral reefs?
Touching can damage or kill coral, disrupting marine ecosystems
96
What is the role of a responsible diver in marine conservation?
Minimize impact, avoid disturbing wildlife, and collect debris if safe
97
What is neutral buoyancy’s role in environmental protection?
Prevents accidental contact with reefs or marine life, reducing damage
98
What should you do if you see marine debris?
Collect it if safe and within your training, or report it to authorities
99
Why is sunscreen harmful to coral reefs?
Chemicals like oxybenzone can bleach and damage coral
100
What is the purpose of marine protected areas (MPAs)?
To conserve marine ecosystems by limiting fishing, diving, or other activities
101
How can divers avoid disturbing marine life?
Maintain distance, avoid chasing animals, and move slowly to prevent stress
102
What is coral bleaching?
When corals expel algae due to stress (e.g., warm water), causing them to turn white and potentially die
103
Why should divers avoid feeding marine animals?
Feeding disrupts natural behaviors and can harm their health
104
What is the PADI AWARE program?
An initiative to promote ocean conservation through education and action

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