PADI Open Water Diver Certification
Scuba Diving Certification Study Guide
Questions and Answers Latest Version
2026/2027 Comprehensive Review
SCUBA - Correct answer Self contained underwater breathing apparatus
What is the pressure change for each 10m/33ft of depth change? - Correct answer 1
bar/1 ata/1 atmosphere
What is the relationship between my depth in water and the pressure? - Correct
answer The deeper you go in water, the more the pressure increases
Pressure is expressed as the weight of air
What is the relationship between pressure, and the volume and the density of air? -
Correct answer As pressure increases, the gas volume decreases and the gas density
increases
,If I take a volume of air from one depth to another depth, how much will the volume
and density change? - Correct answer Volume will be 1/ata#
Density will be ata#
What 3 major body air spaces does increasing pressure affect as I descend? - Correct
answer Ears, sinuses, mask
What is a "squeeze"? - Correct answer The discomfort caused by pressure imbalance
pulling tissue into the air space
What is "equalization"? - Correct answer The addition of air to your air spaces as you
descend
How do I equalize as I descend? - Correct answer For ears and sinuses, pinch your
nose and blow gently, or wiggle your jaw and swallow
For mask, blow into it with nose
,How often should I equalize? - Correct answer Every meter/few feet, BEFORE you feel
discomfort
What should I do if I can't equalize? - Correct answer Stop your descent, signal
problem and point to your ear, ascend a bit, and try again
What can happen if I don't or can't equalize gently and keep descending? - Correct
answer Fluid can rupture the eardrum
Bruising around the face can occur
Why does a congestion from a cold or allergy temporarily keep me from diving? -
Correct answer Congestion might block normal air flow, making equalization difficult
or impossible
Why should I never dive with earplugs? - Correct answer They create air spaces that
you can't equalize
, What other body air spaces are affected by increasing pressure? How do I equalize
them? - Correct answer In filled teeth - go to a dentist
In a dry suit - learn from an instructor
Lungs - breathe normally and continuously
What is the most important rule in scuba diving? - Correct answer Breathe
continuously and never hold your breath
What can happen if I don't follow the most important rule in scuba diving? - Correct
answer Your lungs will over expand and rupture
What is a "reverse block"? - Correct answer When expanding air becomes trapped in
your body air spaces as you ascend
What should I do if I feel discomfort in my ears, sinuses, stomach, intestines, or teeth
while ascending? - Correct answer Stop your ascent and descend a meter/few feet to
reduce discomfort and give trapped air time to work its way out
Scuba Diving Certification Study Guide
Questions and Answers Latest Version
2026/2027 Comprehensive Review
SCUBA - Correct answer Self contained underwater breathing apparatus
What is the pressure change for each 10m/33ft of depth change? - Correct answer 1
bar/1 ata/1 atmosphere
What is the relationship between my depth in water and the pressure? - Correct
answer The deeper you go in water, the more the pressure increases
Pressure is expressed as the weight of air
What is the relationship between pressure, and the volume and the density of air? -
Correct answer As pressure increases, the gas volume decreases and the gas density
increases
,If I take a volume of air from one depth to another depth, how much will the volume
and density change? - Correct answer Volume will be 1/ata#
Density will be ata#
What 3 major body air spaces does increasing pressure affect as I descend? - Correct
answer Ears, sinuses, mask
What is a "squeeze"? - Correct answer The discomfort caused by pressure imbalance
pulling tissue into the air space
What is "equalization"? - Correct answer The addition of air to your air spaces as you
descend
How do I equalize as I descend? - Correct answer For ears and sinuses, pinch your
nose and blow gently, or wiggle your jaw and swallow
For mask, blow into it with nose
,How often should I equalize? - Correct answer Every meter/few feet, BEFORE you feel
discomfort
What should I do if I can't equalize? - Correct answer Stop your descent, signal
problem and point to your ear, ascend a bit, and try again
What can happen if I don't or can't equalize gently and keep descending? - Correct
answer Fluid can rupture the eardrum
Bruising around the face can occur
Why does a congestion from a cold or allergy temporarily keep me from diving? -
Correct answer Congestion might block normal air flow, making equalization difficult
or impossible
Why should I never dive with earplugs? - Correct answer They create air spaces that
you can't equalize
, What other body air spaces are affected by increasing pressure? How do I equalize
them? - Correct answer In filled teeth - go to a dentist
In a dry suit - learn from an instructor
Lungs - breathe normally and continuously
What is the most important rule in scuba diving? - Correct answer Breathe
continuously and never hold your breath
What can happen if I don't follow the most important rule in scuba diving? - Correct
answer Your lungs will over expand and rupture
What is a "reverse block"? - Correct answer When expanding air becomes trapped in
your body air spaces as you ascend
What should I do if I feel discomfort in my ears, sinuses, stomach, intestines, or teeth
while ascending? - Correct answer Stop your ascent and descend a meter/few feet to
reduce discomfort and give trapped air time to work its way out
