SDI Scuba Certification Exam questions with accurate answers
|verified answers 2026!!!
Define SCUBA - ANSWERS💫✔️-S - self
C - contained
U - underwater
B - breathing
A - apparatus
List 3 important scuba diving changes that occurred in 1950s - ANSWERS💫✔️-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 - ANSWERS💫✔️-1) dive tables
2) J-valves
3) depth gauges
What sets SDI apart from other training agencies? - ANSWERS💫✔️-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? - ANSWERS💫✔️-Objects
underwater appear 25% larger and 25% closer
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? - ANSWERS💫✔️-4 times faster
because water is about 800 times denser than air.
What is the first color to be absorbed underwater? - ANSWERS💫✔️-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. - ANSWERS💫✔️-Slack tide
If you are caught in a rip current, first swim _____ to the current to get out of it before swimming
towards shore. - ANSWERS💫✔️-Parallel
Waves are usually caused by - ANSWERS💫✔️-Wind pushing water on the surface
T or F: Anticipate surge action to avoid contact with stationary objects - ANSWERS💫✔️-True
What type of marine life cause most diving injuries? - ANSWERS💫✔️-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? - ANSWERS💫✔️-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? - ANSWERS💫✔️-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)? - ANSWERS💫✔️-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? - ANSWERS💫✔️-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? -
ANSWERS💫✔️-4x
|verified answers 2026!!!
Define SCUBA - ANSWERS💫✔️-S - self
C - contained
U - underwater
B - breathing
A - apparatus
List 3 important scuba diving changes that occurred in 1950s - ANSWERS💫✔️-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 - ANSWERS💫✔️-1) dive tables
2) J-valves
3) depth gauges
What sets SDI apart from other training agencies? - ANSWERS💫✔️-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? - ANSWERS💫✔️-Objects
underwater appear 25% larger and 25% closer
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? - ANSWERS💫✔️-4 times faster
because water is about 800 times denser than air.
What is the first color to be absorbed underwater? - ANSWERS💫✔️-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. - ANSWERS💫✔️-Slack tide
If you are caught in a rip current, first swim _____ to the current to get out of it before swimming
towards shore. - ANSWERS💫✔️-Parallel
Waves are usually caused by - ANSWERS💫✔️-Wind pushing water on the surface
T or F: Anticipate surge action to avoid contact with stationary objects - ANSWERS💫✔️-True
What type of marine life cause most diving injuries? - ANSWERS💫✔️-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? - ANSWERS💫✔️-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? - ANSWERS💫✔️-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)? - ANSWERS💫✔️-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? - ANSWERS💫✔️-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? -
ANSWERS💫✔️-4x
