SDI SCUBA DIVER CERTIFICATION 2026/2027
STUDY GUIDE – FULL EXAM QUESTIONS AND
100% ACCURATE VERIFIED ANSWERS.
◎ 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
◎ 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
◎ 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
◎ What should you do if you experience discomfort in your ears upon descending?
ANSWER:- Immediately stop descending and ascend a few feet until you are shallow
enough not to feel any discomfort
STUDY GUIDE – FULL EXAM QUESTIONS AND
100% ACCURATE VERIFIED ANSWERS.
◎ 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
◎ 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
◎ 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
◎ What should you do if you experience discomfort in your ears upon descending?
ANSWER:- Immediately stop descending and ascend a few feet until you are shallow
enough not to feel any discomfort
