SDI Final Exam
We measure waves by their height and weight.
1: True.
2: False. - ✔️✔️False.
Explanation:
We measure waves by their height and length.
Scuba cylinders must be:
1: Hydrostatically tested every four years and visually inspected every six months.
2: Hydrostatically tested and visually inspected at intervals determined by local laws and
regulations, or prevailing standards of practice.
3: Hydrostatically tested every year and visually inspected every five years.
4: None of the above. - ✔️✔️Correct Answer:
Hydrostatically tested and visually inspected at intervals determined by local laws and
regulations, or prevailing standards of practice.
Explanation:
Scuba cylinders must periodically undergo periodic visual inspections and hydrostatic
tests, at intervals determined by local laws and regulations, or prevailing standards of
practice.
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.
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.
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:
We measure waves by their height and weight.
1: True.
2: False. - ✔️✔️False.
Explanation:
We measure waves by their height and length.
Scuba cylinders must be:
1: Hydrostatically tested every four years and visually inspected every six months.
2: Hydrostatically tested and visually inspected at intervals determined by local laws and
regulations, or prevailing standards of practice.
3: Hydrostatically tested every year and visually inspected every five years.
4: None of the above. - ✔️✔️Correct Answer:
Hydrostatically tested and visually inspected at intervals determined by local laws and
regulations, or prevailing standards of practice.
Explanation:
Scuba cylinders must periodically undergo periodic visual inspections and hydrostatic
tests, at intervals determined by local laws and regulations, or prevailing standards of
practice.
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.
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.
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:
