2024 SDI FINAL EXAM QUESTIONS & CORRECT
ANSWERS
Objects under water appear 60 percent larger than they do on land.
true
As you descend:
Colors appear to fade.
Reds and oranges are among the first colors to disappear.
At 30 m/99 ft, little color remains other than blues, grays, blacks and whites.
All of the above.
Because sound travels faster under water:
It is harder to determine the direction from which a sound is coming.
Which of the following is/are true?
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):
Thermocline
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.
true
Surge is the backwash of water from waves breaking on shore.
false
Which of the following is/are true?
Tidal currents can be very strong, making diving difficult or even dangerous.
What is/are the primary cause(s) of permanent ocean currents?
,The sun warming equatorial ocean water.
Seismic activity deep under water.
The earth's rotation.
Both the first and third answers are correct.
Which of the following statements is/are true?
A rip current is a narrow flow of swiftly moving water that runs perpendicular to
shore.
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.
The force of a rip current generally diminishes in deeper water, not far beyond the
surf zone.
All of the above.
Which of the following best describes the formation of surf?
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.
Which of the following is/are true?
Surge is the back-and-forth movement of water caused by waves passing over
head.
Which of the following is/are true?
Tides can make the water at a particular dive site noticeably deeper or shallower
than you may have experienced previously.
Tidal currents can be very strong, making diving difficult or even dangerous.
Strong tidal currents can have an adverse effect on visibility.
All of the above.
Which of the following is not true?
Longshore currents always move in the same direction.
If caught in a rip current, swim perpendicular to shore, until you are completely out
of the rip current, then swim in towards shore.
, false
Which of the following statements are true?
Wave height is the distance from its highest point (crest) to its lowest point
(trough).
Wave length is the distance from crest to crest.
Wave oscillation to calculated by multiplying the wave height times its length.
Both the first and second answers are correct.
Which of the following is not true?
If the bottom of a wave moves faster than the top, the wave will break.
Surge
Is the back-and-forth movement of water caused by waves passing over head.
In general, the best time to dive is during slack tide, the period between high and
low tides.
true
The sun warming water near the equator, coupled with the earth's rotation, is the
primary cause of permanent ocean currents.
true
Which of the following is/are true?
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.
false
What causes most aquatic animal bites?
An animal's defensive response to a perceived threat.
Sharks.
Mistaken identity.
Both the first and third answers are correct.
ANSWERS
Objects under water appear 60 percent larger than they do on land.
true
As you descend:
Colors appear to fade.
Reds and oranges are among the first colors to disappear.
At 30 m/99 ft, little color remains other than blues, grays, blacks and whites.
All of the above.
Because sound travels faster under water:
It is harder to determine the direction from which a sound is coming.
Which of the following is/are true?
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):
Thermocline
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.
true
Surge is the backwash of water from waves breaking on shore.
false
Which of the following is/are true?
Tidal currents can be very strong, making diving difficult or even dangerous.
What is/are the primary cause(s) of permanent ocean currents?
,The sun warming equatorial ocean water.
Seismic activity deep under water.
The earth's rotation.
Both the first and third answers are correct.
Which of the following statements is/are true?
A rip current is a narrow flow of swiftly moving water that runs perpendicular to
shore.
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.
The force of a rip current generally diminishes in deeper water, not far beyond the
surf zone.
All of the above.
Which of the following best describes the formation of surf?
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.
Which of the following is/are true?
Surge is the back-and-forth movement of water caused by waves passing over
head.
Which of the following is/are true?
Tides can make the water at a particular dive site noticeably deeper or shallower
than you may have experienced previously.
Tidal currents can be very strong, making diving difficult or even dangerous.
Strong tidal currents can have an adverse effect on visibility.
All of the above.
Which of the following is not true?
Longshore currents always move in the same direction.
If caught in a rip current, swim perpendicular to shore, until you are completely out
of the rip current, then swim in towards shore.
, false
Which of the following statements are true?
Wave height is the distance from its highest point (crest) to its lowest point
(trough).
Wave length is the distance from crest to crest.
Wave oscillation to calculated by multiplying the wave height times its length.
Both the first and second answers are correct.
Which of the following is not true?
If the bottom of a wave moves faster than the top, the wave will break.
Surge
Is the back-and-forth movement of water caused by waves passing over head.
In general, the best time to dive is during slack tide, the period between high and
low tides.
true
The sun warming water near the equator, coupled with the earth's rotation, is the
primary cause of permanent ocean currents.
true
Which of the following is/are true?
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.
false
What causes most aquatic animal bites?
An animal's defensive response to a perceived threat.
Sharks.
Mistaken identity.
Both the first and third answers are correct.
