SDI Scuba Exam:SDI: SDI Scuba Certification Exam Study
Guide:SDI Computer Nitrox Exam:SDI Scuba Exam
objects underwater appear ___ and ___ than they do on land - ANSWER:closer and larger
As you descend:
1: Colors will remain largely the same.
2: Blues and grays disappear quickly.
3: Dive lights have little effect on apparent color.
4: None of the above. - ANSWER:4 (none of the above)
Water conducts heat away from your body ____x as fast as air does - ANSWER:25x
When water stratifies itself into layers, according to temperature, the boundary between layers is known
as a(n): - ANSWER:thermocline
Which of the following is/are true?
1: Tides can make the water at a particular dive site noticeably deeper or shallower than you may have
experienced previously.
2: Tidal currents can be very strong, making diving difficult or even dangerous.
3: Strong tidal currents can have an adverse effect on visibility.
4: All of the above. - ANSWER:4 (all of the above)
Which of the following is/are true?
1: Water conducts heat away from your body ten times faster than air does.
2: Water conducts heat away from your body 25 times faster than air does.
3: Fresh water conducts heat away from your body faster than salt water does.
4: Salt water conducts heat away from your body faster than fresh water does. - ANSWER:2 (Water
conducts heat away from your body 25 times faster than air does)
The presence of thermoclines means that:
1: Surface temperatures will provide divers with a good indication of what they can expect at depth.
2: Divers may require less in the way of exposure protection at depth than they will at the surface.
3: Divers may require more in the way of exposure protection at depth than they will at the surface.
4: None of the above. - ANSWER:3 (Divers may require more in the way of exposure protection at depth
than they will at the surface)
,Which of the following statements are true?
1: Wave height is the distance from its highest point (crest) to its lowest point (trough).
2: Wave length is the distance from crest to crest.
3: Wave oscillation to calculated by multiplying the wave height times its length.
4: Both the first and second answers are correct. - ANSWER:4 (both the first and second answers are
correct)
TRUE OR FALSE: In general, the best time to dive is during slack tide, the period between high and low
tides. - ANSWER:TRUE
TRUE OR FALSE: The sun warming water near the equator, coupled with the earth's rotation, is the
primary cause of permanent ocean currents. - ANSWER:True
T/F
A wave encountering shallow water begins to slow at it bottom, while the top of the wave continues at
its previous speed. This causes the wave to break. - ANSWER:true
Which of the following statements is/are true?
1: A rip current is a narrow flow of swiftly moving water that runs perpendicular to shore.
2: Rip currents form when water flowing out to sea is funneled through a narrow restriction, such as two
sandbars or a break in a coral reef.
3: The force of a rip current generally diminishes in deeper water, not far beyond the surf zone.
4: All of the above. - ANSWER:All of the above
Which of the following is/are true?
1: Surge is the backwash of water from waves breaking on shore.
2: Surge is the back-and-forth movement of water caused by waves passing over head.
3: Surge occurs when waves force water between facing rock ledges.
4: None of the above. - ANSWER:2 (Surge is the back-and-forth movement of water caused by waves
passing over head.)
Which of the following best describes the formation of surf?
1: Waves energy, rebounding from its impact with shore, crashes into oncoming waves, causing them to
break.
2: Entering shallow water forces wave energy upward, making the wave crest unstable and causing it to
break.
3: A wave encountering shallow water begins to slow at its bottom, while the top of the wave continues
at its previous speed. This causes the wave to break.
, 4: As waves enter shallow water, the distance between wave crests (wave length) shortens, increasing
the tendency to break. - ANSWER:(3) A wave encountering shallow water begins to slow at its bottom,
while the top of the wave continues at its previous speed. This causes the wave to break.
T/F
Most aquatic life injuries amount to no more than a temporary, yet painful, sting or abrasion. -
ANSWER:true (aquatic life injuries)
T/F
Psoriacysts produce toxins that, when touched, can produce symptoms ranging from a mild rash or sting
to anaphylactic shock or even paralysis. - ANSWER:false (it's actually nematocysts)
Some aquatic animals possess stinging cells. These cells are called:
1: Hypothocysts.
2: Nematocysts.
3: Psoriacysts.
4: None of the above. - ANSWER:2: Nematocysts.
T/F
Depending on circumstances, there are times when divers may wish to be positively, negatively or
neutrally buoyant. - ANSWER:true (buoyant)
A scuba cylinder that normally lasts one hour at the surface will last _______ minutes at 20 meters/66
feet. - ANSWER:20 minutes
Which of the following is not true? Divers should equalize:
1: Preemptively before descent.
2: Well before feeling any pain or discomfort.
3: As soon as they feel any pain or discomfort.
4: Early and often during descent. - ANSWER:3 (as soon as they feel any pan or discomfort)
T/F
Taking decongestants is a good way to reduce the risk of ear or sinus squeeze. - ANSWER:false (squeeze)
All of the following are true except:
1: You can help prevent mask squeeze by exhaling periodically into your mask during ascent.
2: Regular dental care and ensuring your teeth are free of gas spaces can help prevent tooth squeeze.
3: If you experience a reverse block, descend to a point where the pain subsides, then ascend slowly
while wiggling your jaw and swallowing. Repeat this process as needed until you can ascend without
pain or discomfort.
Guide:SDI Computer Nitrox Exam:SDI Scuba Exam
objects underwater appear ___ and ___ than they do on land - ANSWER:closer and larger
As you descend:
1: Colors will remain largely the same.
2: Blues and grays disappear quickly.
3: Dive lights have little effect on apparent color.
4: None of the above. - ANSWER:4 (none of the above)
Water conducts heat away from your body ____x as fast as air does - ANSWER:25x
When water stratifies itself into layers, according to temperature, the boundary between layers is known
as a(n): - ANSWER:thermocline
Which of the following is/are true?
1: Tides can make the water at a particular dive site noticeably deeper or shallower than you may have
experienced previously.
2: Tidal currents can be very strong, making diving difficult or even dangerous.
3: Strong tidal currents can have an adverse effect on visibility.
4: All of the above. - ANSWER:4 (all of the above)
Which of the following is/are true?
1: Water conducts heat away from your body ten times faster than air does.
2: Water conducts heat away from your body 25 times faster than air does.
3: Fresh water conducts heat away from your body faster than salt water does.
4: Salt water conducts heat away from your body faster than fresh water does. - ANSWER:2 (Water
conducts heat away from your body 25 times faster than air does)
The presence of thermoclines means that:
1: Surface temperatures will provide divers with a good indication of what they can expect at depth.
2: Divers may require less in the way of exposure protection at depth than they will at the surface.
3: Divers may require more in the way of exposure protection at depth than they will at the surface.
4: None of the above. - ANSWER:3 (Divers may require more in the way of exposure protection at depth
than they will at the surface)
,Which of the following statements are true?
1: Wave height is the distance from its highest point (crest) to its lowest point (trough).
2: Wave length is the distance from crest to crest.
3: Wave oscillation to calculated by multiplying the wave height times its length.
4: Both the first and second answers are correct. - ANSWER:4 (both the first and second answers are
correct)
TRUE OR FALSE: In general, the best time to dive is during slack tide, the period between high and low
tides. - ANSWER:TRUE
TRUE OR FALSE: The sun warming water near the equator, coupled with the earth's rotation, is the
primary cause of permanent ocean currents. - ANSWER:True
T/F
A wave encountering shallow water begins to slow at it bottom, while the top of the wave continues at
its previous speed. This causes the wave to break. - ANSWER:true
Which of the following statements is/are true?
1: A rip current is a narrow flow of swiftly moving water that runs perpendicular to shore.
2: Rip currents form when water flowing out to sea is funneled through a narrow restriction, such as two
sandbars or a break in a coral reef.
3: The force of a rip current generally diminishes in deeper water, not far beyond the surf zone.
4: All of the above. - ANSWER:All of the above
Which of the following is/are true?
1: Surge is the backwash of water from waves breaking on shore.
2: Surge is the back-and-forth movement of water caused by waves passing over head.
3: Surge occurs when waves force water between facing rock ledges.
4: None of the above. - ANSWER:2 (Surge is the back-and-forth movement of water caused by waves
passing over head.)
Which of the following best describes the formation of surf?
1: Waves energy, rebounding from its impact with shore, crashes into oncoming waves, causing them to
break.
2: Entering shallow water forces wave energy upward, making the wave crest unstable and causing it to
break.
3: A wave encountering shallow water begins to slow at its bottom, while the top of the wave continues
at its previous speed. This causes the wave to break.
, 4: As waves enter shallow water, the distance between wave crests (wave length) shortens, increasing
the tendency to break. - ANSWER:(3) A wave encountering shallow water begins to slow at its bottom,
while the top of the wave continues at its previous speed. This causes the wave to break.
T/F
Most aquatic life injuries amount to no more than a temporary, yet painful, sting or abrasion. -
ANSWER:true (aquatic life injuries)
T/F
Psoriacysts produce toxins that, when touched, can produce symptoms ranging from a mild rash or sting
to anaphylactic shock or even paralysis. - ANSWER:false (it's actually nematocysts)
Some aquatic animals possess stinging cells. These cells are called:
1: Hypothocysts.
2: Nematocysts.
3: Psoriacysts.
4: None of the above. - ANSWER:2: Nematocysts.
T/F
Depending on circumstances, there are times when divers may wish to be positively, negatively or
neutrally buoyant. - ANSWER:true (buoyant)
A scuba cylinder that normally lasts one hour at the surface will last _______ minutes at 20 meters/66
feet. - ANSWER:20 minutes
Which of the following is not true? Divers should equalize:
1: Preemptively before descent.
2: Well before feeling any pain or discomfort.
3: As soon as they feel any pain or discomfort.
4: Early and often during descent. - ANSWER:3 (as soon as they feel any pan or discomfort)
T/F
Taking decongestants is a good way to reduce the risk of ear or sinus squeeze. - ANSWER:false (squeeze)
All of the following are true except:
1: You can help prevent mask squeeze by exhaling periodically into your mask during ascent.
2: Regular dental care and ensuring your teeth are free of gas spaces can help prevent tooth squeeze.
3: If you experience a reverse block, descend to a point where the pain subsides, then ascend slowly
while wiggling your jaw and swallowing. Repeat this process as needed until you can ascend without
pain or discomfort.
