1 | P a g e | © copyright 2024/2025 | Grade A+
SDI Scuba Certification Exam Study
Guide Questions and Answers
(100% Pass)
Define SCUBA
→ S - self
→ C - contained
→ U - underwater
→ B - breathing
→ A - apparatus
List 3 important scuba diving changes that occurred in 1950s
→ 1) published USN dive tables
→ 2) invented the personal dive computer
→ 3) equipment manufacturers made improvements to the design and
workmanship of gear
Name 3 different devices that modern dive computers replace
→ 1) dive tables
→ 2) J-valves
→ 3) depth gauges
What sets SDI apart from other training agencies?
→ First dive training agency to provide entry level scuba instruction that
incorporates the use of personal dive computers --> more streamlined
scuba course w/ more instruction time in the water
How much larger and closer do objects appear underwater and why?
→ Objects underwater appear 25% larger and 25% closer
Master01 | September, 2024/2025 | Latest update
, 1 | P a g e | © copyright 2024/2025 | Grade A+
As light travels through the airspace created by the mask, it bends, creating
a magnifying effect.
How much faster does sound move through water than air and why?
→ 4 times faster because water is about 800 times denser than air.
What is the first color to be absorbed underwater?
→ Red (within first 25 feet)
When diving from shore, the best time to dive is when there is the least
amount of tidal current. _______ tide is when there is no horizontal water
movement.
→ Slack tide
If you are caught in a rip current, first swim _____ to the current to get out of it
before swimming towards shore.
→ Parallel
Waves are usually caused by
→ Wind pushing water on the surface
T or F: Anticipate surge action to avoid contact with stationary objects
→ True
What type of marine life cause most diving injuries?
Master01 | September, 2024/2025 | Latest update
, 1 | P a g e | © copyright 2024/2025 | Grade A+
→ Most diving injuries result from animal's defensive response to a
perceived threat
What should you do if you see a potentially dangerous animal underwater
and it does not leave the area?
→ Remain still and calm. Slowly leave area if necessary.
List three different reasons that it is advisable to check with your local dive
center before conducting a dive in an area you are unfamiliar with?
→ 1) tidal conditions
2) marine life
3) first aid for potential injuries in area
What is the absolute pressure (in atm/bar) at 20 meters (66 feet)?
→ 3 atm/bar
What will be the volume in a ball that is filled with 2 cubic feet/liters of air at
30 meters (90 feet) when it is taken to surface?
→ 8 cubic feet/liter (4x the volume)
How many more times dense is the air in a ballon at 4 atm/bar compared to
air density at surface?
→ 4x
If a scuba cylinder lasts two hours at sea level, how long will it last at 20 m/66
ft?
Master01 | September, 2024/2025 | Latest update
SDI Scuba Certification Exam Study
Guide Questions and Answers
(100% Pass)
Define SCUBA
→ S - self
→ C - contained
→ U - underwater
→ B - breathing
→ A - apparatus
List 3 important scuba diving changes that occurred in 1950s
→ 1) published USN dive tables
→ 2) invented the personal dive computer
→ 3) equipment manufacturers made improvements to the design and
workmanship of gear
Name 3 different devices that modern dive computers replace
→ 1) dive tables
→ 2) J-valves
→ 3) depth gauges
What sets SDI apart from other training agencies?
→ First dive training agency to provide entry level scuba instruction that
incorporates the use of personal dive computers --> more streamlined
scuba course w/ more instruction time in the water
How much larger and closer do objects appear underwater and why?
→ Objects underwater appear 25% larger and 25% closer
Master01 | September, 2024/2025 | Latest update
, 1 | P a g e | © copyright 2024/2025 | Grade A+
As light travels through the airspace created by the mask, it bends, creating
a magnifying effect.
How much faster does sound move through water than air and why?
→ 4 times faster because water is about 800 times denser than air.
What is the first color to be absorbed underwater?
→ Red (within first 25 feet)
When diving from shore, the best time to dive is when there is the least
amount of tidal current. _______ tide is when there is no horizontal water
movement.
→ Slack tide
If you are caught in a rip current, first swim _____ to the current to get out of it
before swimming towards shore.
→ Parallel
Waves are usually caused by
→ Wind pushing water on the surface
T or F: Anticipate surge action to avoid contact with stationary objects
→ True
What type of marine life cause most diving injuries?
Master01 | September, 2024/2025 | Latest update
, 1 | P a g e | © copyright 2024/2025 | Grade A+
→ Most diving injuries result from animal's defensive response to a
perceived threat
What should you do if you see a potentially dangerous animal underwater
and it does not leave the area?
→ Remain still and calm. Slowly leave area if necessary.
List three different reasons that it is advisable to check with your local dive
center before conducting a dive in an area you are unfamiliar with?
→ 1) tidal conditions
2) marine life
3) first aid for potential injuries in area
What is the absolute pressure (in atm/bar) at 20 meters (66 feet)?
→ 3 atm/bar
What will be the volume in a ball that is filled with 2 cubic feet/liters of air at
30 meters (90 feet) when it is taken to surface?
→ 8 cubic feet/liter (4x the volume)
How many more times dense is the air in a ballon at 4 atm/bar compared to
air density at surface?
→ 4x
If a scuba cylinder lasts two hours at sea level, how long will it last at 20 m/66
ft?
Master01 | September, 2024/2025 | Latest update
