SDI Final Exam | 65 Questions with Correct Answers
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1. Objects under water appear:
1: The same size as they do on land.
2: Twice as large as they do on land.
3: Closer and larger than they do on land.
4: Smaller and farther away than they do on land.:
Answer: Closer and larger than they do on land.
2. As you descend:
1: Colors appear to fade.
2: Reds and oranges are among the first colors to disappear.
3: At 30 m/99 ft, little color remains other than blues, grays, blacks and whites.
4: All of the above.:
Answer: All of the above.
3. Which of the following statements is true? There may be more than one
correct answer.
,1: Water is 400 times denser than air.
2: Water is 800 times denser than air.
3: Sound travels about four times faster underwater.
4: Both the second and the third answer are correct.:
Answer: Both the second and the third answer are correct.
4. 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: Water conducts heat away from your body 25 times faster than air does.
5. When water stratifies itself into layers, according to temperature, the bound-
ary between layers is known as a(n):
1: Halocline.
2: Ichtyocline.
3: Thermodyne.
4: Thermocline.:
Answer: Thermocline.
,6. 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: All of the above.
7. The sun warming water near the equator, coupled with the earth's rotation,
is the primary cause of permanent ocean currents.
1: True.
2: False.:
Answer: True.
8. Which of the following is/are true?
1: If caught in a rip current, swim directly towards shore, using the most
powerful kick possible.
2: If caught in a rip current, swim perpendicular to shore, until you are com-
pletely out of the rip current, then swim in towards shore.
3: If caught in a rip current, swim parallel to shore, until you are completely out
, of the rip current, then swim in towards shore.
4: Don't fight the rip current; relax and let it carry you closer to shore.:
Answer: If caught in a rip current, swim parallel to shore, until you are completely out of the rip current, then
swim in towards shore.
9. We measure waves by their height and weight.
1: True.
2: False.:
Answer: False.
Explanation:
We measure waves by their height and length.
10. Which of the following best describes the formation of surf?
1: Waves energy, rebounding from its impact with shore, crashes into oncom-
ing 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
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1. Objects under water appear:
1: The same size as they do on land.
2: Twice as large as they do on land.
3: Closer and larger than they do on land.
4: Smaller and farther away than they do on land.:
Answer: Closer and larger than they do on land.
2. As you descend:
1: Colors appear to fade.
2: Reds and oranges are among the first colors to disappear.
3: At 30 m/99 ft, little color remains other than blues, grays, blacks and whites.
4: All of the above.:
Answer: All of the above.
3. Which of the following statements is true? There may be more than one
correct answer.
,1: Water is 400 times denser than air.
2: Water is 800 times denser than air.
3: Sound travels about four times faster underwater.
4: Both the second and the third answer are correct.:
Answer: Both the second and the third answer are correct.
4. 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: Water conducts heat away from your body 25 times faster than air does.
5. When water stratifies itself into layers, according to temperature, the bound-
ary between layers is known as a(n):
1: Halocline.
2: Ichtyocline.
3: Thermodyne.
4: Thermocline.:
Answer: Thermocline.
,6. 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: All of the above.
7. The sun warming water near the equator, coupled with the earth's rotation,
is the primary cause of permanent ocean currents.
1: True.
2: False.:
Answer: True.
8. Which of the following is/are true?
1: If caught in a rip current, swim directly towards shore, using the most
powerful kick possible.
2: If caught in a rip current, swim perpendicular to shore, until you are com-
pletely out of the rip current, then swim in towards shore.
3: If caught in a rip current, swim parallel to shore, until you are completely out
, of the rip current, then swim in towards shore.
4: Don't fight the rip current; relax and let it carry you closer to shore.:
Answer: If caught in a rip current, swim parallel to shore, until you are completely out of the rip current, then
swim in towards shore.
9. We measure waves by their height and weight.
1: True.
2: False.:
Answer: False.
Explanation:
We measure waves by their height and length.
10. Which of the following best describes the formation of surf?
1: Waves energy, rebounding from its impact with shore, crashes into oncom-
ing 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
