Page | 1
SDI Scuba Certification Exam Study
Guide Questions with Detailed Verified
Answers
Question: Define SCUBA
Answer: S - self
C - contained
U - underwater
B - breathing
A - apparatus
Question:List 3 important scuba diving changes that occurred in 1950s
Answer: 1) published USN dive tables
2) invented the personal dive computer
3) equipment manufacturers made improvements to the design and
workmanship of gear
Question:Name 3 different devices that modern dive computers replace
Answer: 1) dive tables
2) J-valves
3) depth gauges
Question:What sets SDI apart from other training agencies?
, Page | 2
Answer: 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
Question:How much larger and closer do objects appear underwater and
why?
Answer: Objects underwater appear 25% larger and 25% closer
As light travels through the airspace created by the mask, it bends, creating a
magnifying effect.
Question:How much faster does sound move through water than air and
why?
Answer: 4 times faster because water is about 800 times denser than air.
Question:What is the first color to be absorbed underwater?
Answer: Red (within first 25 feet)
Question: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.
Answer: Slack tide
Question:If you are caught in a rip current, first swim _____ to the current to
get out of it before swimming towards shore.
Answer: Parallel
, Page | 3
Question:Waves are usually caused by
Answer: Wind pushing water on the surface
Question:T or F: Anticipate surge action to avoid contact with stationary
objects
Answer: True
Question:What type of marine life cause most diving injuries?
Answer: Most diving injuries result from animal's defensive response to a
perceived threat
Question:What should you do if you see a potentially dangerous animal
underwater and it does not leave the area?
Answer: Remain still and calm. Slowly leave area if necessary.
Question: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?
Answer: 1) tidal conditions
2) marine life
3) first aid for potential injuries in area
Question:What is the absolute pressure (in atm/bar) at 20 meters (66 feet)?
Answer: 3 atm/bar
Question: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?
Answer: 8 cubic feet/liter (4x the volume)
SDI Scuba Certification Exam Study
Guide Questions with Detailed Verified
Answers
Question: Define SCUBA
Answer: S - self
C - contained
U - underwater
B - breathing
A - apparatus
Question:List 3 important scuba diving changes that occurred in 1950s
Answer: 1) published USN dive tables
2) invented the personal dive computer
3) equipment manufacturers made improvements to the design and
workmanship of gear
Question:Name 3 different devices that modern dive computers replace
Answer: 1) dive tables
2) J-valves
3) depth gauges
Question:What sets SDI apart from other training agencies?
, Page | 2
Answer: 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
Question:How much larger and closer do objects appear underwater and
why?
Answer: Objects underwater appear 25% larger and 25% closer
As light travels through the airspace created by the mask, it bends, creating a
magnifying effect.
Question:How much faster does sound move through water than air and
why?
Answer: 4 times faster because water is about 800 times denser than air.
Question:What is the first color to be absorbed underwater?
Answer: Red (within first 25 feet)
Question: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.
Answer: Slack tide
Question:If you are caught in a rip current, first swim _____ to the current to
get out of it before swimming towards shore.
Answer: Parallel
, Page | 3
Question:Waves are usually caused by
Answer: Wind pushing water on the surface
Question:T or F: Anticipate surge action to avoid contact with stationary
objects
Answer: True
Question:What type of marine life cause most diving injuries?
Answer: Most diving injuries result from animal's defensive response to a
perceived threat
Question:What should you do if you see a potentially dangerous animal
underwater and it does not leave the area?
Answer: Remain still and calm. Slowly leave area if necessary.
Question: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?
Answer: 1) tidal conditions
2) marine life
3) first aid for potential injuries in area
Question:What is the absolute pressure (in atm/bar) at 20 meters (66 feet)?
Answer: 3 atm/bar
Question: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?
Answer: 8 cubic feet/liter (4x the volume)
