SSI SCIENCE OF DIVING 2026 STUDY GUIDE QUESTIONS
AND ANSWERS RATED A+
✔✔Breathing gas consumption:
Varies inversely with depth
Increases as depth increases
Remains the same as depth increases
Decreases as depth increases - ✔✔Increases as depth increases
✔✔If 0.10 cubic feet of air is needed in your buoyancy compensator to maintain neutral
buoyancy at 30 feet in the ocean, what will happen to your buoyancy if you ascend 10
feet without deflating?:
You will stay neutral, even if if you ascend or descend
Your positive buoyancy will increase
There will be no change in buoyancy
Your negative buoyancy will increase - ✔✔Your positive buoyancy will increase
✔✔For every foot of depth in freshwater, pressure changes by:
0.432 psi
0.147 psi
0.445 psi
0.864 psi - ✔✔0.432 psi
✔✔A diver and their equipment weighs 175 lbs. and is neutrally buoyant in saltwater. To
be neutrally buoyant in freshwater, diving with the same equipment, they must:
Remove weight
All answers are correct
Use the same weight
Add weight - ✔✔Remove weight
✔✔How much breathing gas does an 80 cubic foot (3000 psi-rated) cylinder contain if
the fill pressure is 2200 psi, and the temperature remains constant?
40.4 cubic feet
53.9 cubic feet
66.0 cubic feet
58.7 cubic feet - ✔✔58.7 cubic feet
✔✔The partial pressure law (Dalton) requires the sum of the partial pressures to always
be equal with which pressure?
Hydrostatic
Absolute
Atmospheric
All answers are correct - ✔✔Absolute
,✔✔Which physical law states: "If temperature remains constant, the pressure and
volume of any gas are inversely related"?
Dalton's
Archimedes
Henry's
Boyles - ✔✔Boyles
✔✔Assuming a maximum oxygen partial pressure limitation of 1.4 ATA, the MOD for a
40% nitrox mixture in the ocean is:
70.4 feet
120.0 feet
95.0 feet
82.5 feet - ✔✔82.5 feet
✔✔The cardiovascular system consists of these three major components:
Heart (pump), blood (transport medium), and blood vessels (plumbing)
Sinuses and lungs only
Right atrium, left atrium and arteries only
Alveoli, veins and lungs only - ✔✔Heart (pump), blood (transport medium), and blood
vessels (plumbing)
✔✔Permanent hearing loss, vertigo and ringing in the ear are most likely to be the result
of a ruptured:
Semicircular Canal
Round and/or Oval Window
Eustachian Tube
Eardrum - ✔✔Round and/or Oval Window
✔✔The recommended method to avoid sinus squeezes and reverse blocks is to:
Ascend and descend slowly to allow gradual equalization
Only use decongestants that do not produce side effects
Dive only when your sinuses are healthy and clear
Forcibly equalize the pressure in your sinuses every few feet - ✔✔Dive only when your
sinuses are healthy and clear
✔✔If you have difficulty equalizing pressure in your ears/sinuses while descending, you
should:
Ascend 6 feet and force equalization
Stop and wait until the discomfort subsides
Ascend until the pressure is relieved and then attempt equalization
Return to the surface and re-initiate the descent - ✔✔Ascend until the pressure is
relieved and then attempt equalization
✔✔As you dive deeper, the narcotic effect of nitrogen gets:
, Greater
Consistent
Less
No answer is correct - ✔✔Greater
✔✔Nitrogen narcosis begins to affect the average diver at a depth of:
40-45 feet
79-118 feet
60-98 feet
98-132 feet - ✔✔60-98 feet
✔✔What would your minimum surface interval be if you wanted to make two dives to 60
feet for 30 minutes each?
2:00
2:29
1:16
2:39 - ✔✔2:29
✔✔After a 2:45 surface interval as a group D diver, what is your new group
designation?
A
D
C
B - ✔✔B
✔✔What is the maximum allowed time on a dive to 52 feet after a dive to 72 feet for 30
minutes and a 1:45 surface interval?
20 minutes
30 minutes
35 minutes
45 minutes - ✔✔20 minutes
✔✔After a surface interval, you are a D diver. You wish to make a dive to 42 feet. What
is your Residual Time (RT)?
33
21
29
45
Save - ✔✔29
✔✔Which of the following is not a symptom of decompression sickness?
Cyanosis (bluish skin color)
Extreme fatigue
Weakness
AND ANSWERS RATED A+
✔✔Breathing gas consumption:
Varies inversely with depth
Increases as depth increases
Remains the same as depth increases
Decreases as depth increases - ✔✔Increases as depth increases
✔✔If 0.10 cubic feet of air is needed in your buoyancy compensator to maintain neutral
buoyancy at 30 feet in the ocean, what will happen to your buoyancy if you ascend 10
feet without deflating?:
You will stay neutral, even if if you ascend or descend
Your positive buoyancy will increase
There will be no change in buoyancy
Your negative buoyancy will increase - ✔✔Your positive buoyancy will increase
✔✔For every foot of depth in freshwater, pressure changes by:
0.432 psi
0.147 psi
0.445 psi
0.864 psi - ✔✔0.432 psi
✔✔A diver and their equipment weighs 175 lbs. and is neutrally buoyant in saltwater. To
be neutrally buoyant in freshwater, diving with the same equipment, they must:
Remove weight
All answers are correct
Use the same weight
Add weight - ✔✔Remove weight
✔✔How much breathing gas does an 80 cubic foot (3000 psi-rated) cylinder contain if
the fill pressure is 2200 psi, and the temperature remains constant?
40.4 cubic feet
53.9 cubic feet
66.0 cubic feet
58.7 cubic feet - ✔✔58.7 cubic feet
✔✔The partial pressure law (Dalton) requires the sum of the partial pressures to always
be equal with which pressure?
Hydrostatic
Absolute
Atmospheric
All answers are correct - ✔✔Absolute
,✔✔Which physical law states: "If temperature remains constant, the pressure and
volume of any gas are inversely related"?
Dalton's
Archimedes
Henry's
Boyles - ✔✔Boyles
✔✔Assuming a maximum oxygen partial pressure limitation of 1.4 ATA, the MOD for a
40% nitrox mixture in the ocean is:
70.4 feet
120.0 feet
95.0 feet
82.5 feet - ✔✔82.5 feet
✔✔The cardiovascular system consists of these three major components:
Heart (pump), blood (transport medium), and blood vessels (plumbing)
Sinuses and lungs only
Right atrium, left atrium and arteries only
Alveoli, veins and lungs only - ✔✔Heart (pump), blood (transport medium), and blood
vessels (plumbing)
✔✔Permanent hearing loss, vertigo and ringing in the ear are most likely to be the result
of a ruptured:
Semicircular Canal
Round and/or Oval Window
Eustachian Tube
Eardrum - ✔✔Round and/or Oval Window
✔✔The recommended method to avoid sinus squeezes and reverse blocks is to:
Ascend and descend slowly to allow gradual equalization
Only use decongestants that do not produce side effects
Dive only when your sinuses are healthy and clear
Forcibly equalize the pressure in your sinuses every few feet - ✔✔Dive only when your
sinuses are healthy and clear
✔✔If you have difficulty equalizing pressure in your ears/sinuses while descending, you
should:
Ascend 6 feet and force equalization
Stop and wait until the discomfort subsides
Ascend until the pressure is relieved and then attempt equalization
Return to the surface and re-initiate the descent - ✔✔Ascend until the pressure is
relieved and then attempt equalization
✔✔As you dive deeper, the narcotic effect of nitrogen gets:
, Greater
Consistent
Less
No answer is correct - ✔✔Greater
✔✔Nitrogen narcosis begins to affect the average diver at a depth of:
40-45 feet
79-118 feet
60-98 feet
98-132 feet - ✔✔60-98 feet
✔✔What would your minimum surface interval be if you wanted to make two dives to 60
feet for 30 minutes each?
2:00
2:29
1:16
2:39 - ✔✔2:29
✔✔After a 2:45 surface interval as a group D diver, what is your new group
designation?
A
D
C
B - ✔✔B
✔✔What is the maximum allowed time on a dive to 52 feet after a dive to 72 feet for 30
minutes and a 1:45 surface interval?
20 minutes
30 minutes
35 minutes
45 minutes - ✔✔20 minutes
✔✔After a surface interval, you are a D diver. You wish to make a dive to 42 feet. What
is your Residual Time (RT)?
33
21
29
45
Save - ✔✔29
✔✔Which of the following is not a symptom of decompression sickness?
Cyanosis (bluish skin color)
Extreme fatigue
Weakness
