SDI Final Exam Questions with 100%
Correct Answers (Updated 2026)
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.
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
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.
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.
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. - 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.
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.
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.
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. - ANSWER-Thermocline.
We measure waves by their height and weight.
1: True.
2: False. - ANSWER-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. - ANSWER-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:
1: Occurs when waves force water between facing rock ledges.
2: Is the back-and-forth movement of water caused by waves passing over head.
3: Is the backwash of water from waves breaking on shore.
4: None of the above. - ANSWER-Surge is the back-and-forth movement of water
caused by waves passing over head.
Which 'if any' of the following are true?
1: Aquatic animals present a greater risk to divers than any other factor.
2: Most aquatic animal bites result from an animal's defensive response to a perceived
threat or, on rare occasions, from a case of mistaken identify.
Correct Answers (Updated 2026)
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.
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
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.
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.
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. - 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.
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.
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.
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. - ANSWER-Thermocline.
We measure waves by their height and weight.
1: True.
2: False. - ANSWER-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. - ANSWER-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:
1: Occurs when waves force water between facing rock ledges.
2: Is the back-and-forth movement of water caused by waves passing over head.
3: Is the backwash of water from waves breaking on shore.
4: None of the above. - ANSWER-Surge is the back-and-forth movement of water
caused by waves passing over head.
Which 'if any' of the following are true?
1: Aquatic animals present a greater risk to divers than any other factor.
2: Most aquatic animal bites result from an animal's defensive response to a perceived
threat or, on rare occasions, from a case of mistaken identify.
