1 | P a g e | © copyright 2025/2026 | Grade A+
SDI Final Exam Questions and Answers
| Latest Update 2025/2026
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.
~~> Closer and larger than they do on land.
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.
~~> All of the above.
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.
, ~~> Both the second and the third answer are correct.
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.
~~> Water conducts heat away from your body 25 times faster than air
does.
When water stratifies itself into layers, according to temperature, the
boundary between layers is known as a(n):
1: Halocline.
2: Ichtyocline.
3: Thermodyne.
4: Thermocline.
~~> 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.
~~> All of the above.
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.
~~> True.
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
completely 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.
~~> If caught in a rip current, swim parallel to shore, until you are
completely out of the rip current, then swim in towards shore.
, We measure waves by their height and weight.
1: True.
2: False.
~~> False.
Explanation:
We measure waves by their height and length.
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.
~~> Only the third answer (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) is correct.
Surge:
SDI Final Exam Questions and Answers
| Latest Update 2025/2026
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.
~~> Closer and larger than they do on land.
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.
~~> All of the above.
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.
, ~~> Both the second and the third answer are correct.
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.
~~> Water conducts heat away from your body 25 times faster than air
does.
When water stratifies itself into layers, according to temperature, the
boundary between layers is known as a(n):
1: Halocline.
2: Ichtyocline.
3: Thermodyne.
4: Thermocline.
~~> 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.
~~> All of the above.
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.
~~> True.
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
completely 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.
~~> If caught in a rip current, swim parallel to shore, until you are
completely out of the rip current, then swim in towards shore.
, We measure waves by their height and weight.
1: True.
2: False.
~~> False.
Explanation:
We measure waves by their height and length.
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.
~~> Only the third answer (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) is correct.
Surge:
