SDI Certification Exam Review
Questions and Answers
What sets SDI apart from other training agencies? - ANSWER-Students use a personal
dive computer for all instruction and certification dives
How much larger and closer do objects appear under water and why? - ANSWER-33%
larger, 25% closer
Light bends in the air-space between the lens and your eyes.
How much faster does sound move through water than air and why? - ANSWER-4
times faster in water
Water is 800x denser than air; sound travels through denser mediums at faster rates
What is the first color absorbed underwater? - ANSWER-RED (followed by OYGBIV)
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
If you are caught in a rip current, first swim _____ to the current to get out of it before
swimming towards shore. - ANSWER-Perpendicular
Start your dive by swimming ____ the current - ANSWER-into/against
What does SCUBA stand for? - ANSWER-Self
Contained
Underwater
Breathing
Apparatus
List the three important scuba diving changes that occurred in the 1950s - ANSWER-1)
Dive tables published for repetitive dives
2) Improved design/quality of scuba gear
3) Dive computers commercially available
Name three different devices that modern dive computers replace - ANSWER-Depth
gauge, dive tables, watch
Global currents are _____.
Local currents ____. - ANSWER-Fixed
Fluctuate
Rip current - ANSWER-Current which goes seaward due to ocean floor stuctures
, Long shore current - ANSWER-Flows parallel to shore
Waves are caused by - ANSWER-energy generated by WIND
Tides are caused by - ANSWER-polarity of the moon
T/F: Anticipate surge action to avoid contact with stationary objects. - ANSWER-True
What is surge - ANSWER-Back and forth motion underwater which you shouldn't fight;
move deeper and away from dangerous objects if caught in one. USE THEM TO YOUR
ADVANTAGE
What types of marine life cause most diving injuries - ANSWER-Jellyfish or marine life
which account for a temporary, painful sting. WATCH OUT FOR ALLERGIC
REACTIONS.
Injuries due to marine life typically a _____ response - ANSWER-Defense
How do you treat a sting? - ANSWER-Hot water or vinegar
What should you do if a potentially dangerous animal underwater does not leave your
area? - ANSWER-Remain still
Remain calm
Slowly leave area
List three different reasons that it is advisable to check with your local dive center before
diving in an unfamiliar area. - ANSWER-1) Rip currents could be prevalent
2) Thermoclines could affect thermal protection
3) YOU ARE SUBJECT TO LOCALITY (be aware of laws and regulations
What is the absolute pressure in atm at 20m/66ft? - ANSWER-3 atm absolute
What will be the volume in a ball that is filled with 2 cubic feet of air at 30 m/99ft when it
is taken to the surface? - ANSWER-8 cubic feet
How many times more dense is air in a balloon at 4 atm compared to the air density at
the surface? - ANSWER-4 times
If a scuba cylinder lasts two hours at sea level, how long will it last at 20 m/66 ft? -
ANSWER-40 min
How often should you equalize during descent? - ANSWER-Early and often; at the
surface and then every couple feet so no discomfort is felt
Questions and Answers
What sets SDI apart from other training agencies? - ANSWER-Students use a personal
dive computer for all instruction and certification dives
How much larger and closer do objects appear under water and why? - ANSWER-33%
larger, 25% closer
Light bends in the air-space between the lens and your eyes.
How much faster does sound move through water than air and why? - ANSWER-4
times faster in water
Water is 800x denser than air; sound travels through denser mediums at faster rates
What is the first color absorbed underwater? - ANSWER-RED (followed by OYGBIV)
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
If you are caught in a rip current, first swim _____ to the current to get out of it before
swimming towards shore. - ANSWER-Perpendicular
Start your dive by swimming ____ the current - ANSWER-into/against
What does SCUBA stand for? - ANSWER-Self
Contained
Underwater
Breathing
Apparatus
List the three important scuba diving changes that occurred in the 1950s - ANSWER-1)
Dive tables published for repetitive dives
2) Improved design/quality of scuba gear
3) Dive computers commercially available
Name three different devices that modern dive computers replace - ANSWER-Depth
gauge, dive tables, watch
Global currents are _____.
Local currents ____. - ANSWER-Fixed
Fluctuate
Rip current - ANSWER-Current which goes seaward due to ocean floor stuctures
, Long shore current - ANSWER-Flows parallel to shore
Waves are caused by - ANSWER-energy generated by WIND
Tides are caused by - ANSWER-polarity of the moon
T/F: Anticipate surge action to avoid contact with stationary objects. - ANSWER-True
What is surge - ANSWER-Back and forth motion underwater which you shouldn't fight;
move deeper and away from dangerous objects if caught in one. USE THEM TO YOUR
ADVANTAGE
What types of marine life cause most diving injuries - ANSWER-Jellyfish or marine life
which account for a temporary, painful sting. WATCH OUT FOR ALLERGIC
REACTIONS.
Injuries due to marine life typically a _____ response - ANSWER-Defense
How do you treat a sting? - ANSWER-Hot water or vinegar
What should you do if a potentially dangerous animal underwater does not leave your
area? - ANSWER-Remain still
Remain calm
Slowly leave area
List three different reasons that it is advisable to check with your local dive center before
diving in an unfamiliar area. - ANSWER-1) Rip currents could be prevalent
2) Thermoclines could affect thermal protection
3) YOU ARE SUBJECT TO LOCALITY (be aware of laws and regulations
What is the absolute pressure in atm at 20m/66ft? - ANSWER-3 atm absolute
What will be the volume in a ball that is filled with 2 cubic feet of air at 30 m/99ft when it
is taken to the surface? - ANSWER-8 cubic feet
How many times more dense is air in a balloon at 4 atm compared to the air density at
the surface? - ANSWER-4 times
If a scuba cylinder lasts two hours at sea level, how long will it last at 20 m/66 ft? -
ANSWER-40 min
How often should you equalize during descent? - ANSWER-Early and often; at the
surface and then every couple feet so no discomfort is felt
