15 questions modeled on the Instructor exam. Answer all 15, then get your score with a full explanation for every answer — no account needed.
1A staff member tells a family that any child, regardless of age, can join Discover Local Diving. Evaluating this against standards, the statement is:
Why: The staff member's claim is incorrect because Discover Local Diving requires a minimum participant age of 10.
2A search-and-recovery instructor is teaching students to find a small dropped item in an area with limited visibility, using compass headings only. Which pattern fits this scenario best?
Why: The expanding square pattern fits compass-only, small-area, low-visibility searches best.
3A piece of equipment recycles and scrubs exhaled gas of carbon dioxide instead of venting it into the water. This is the opposite of which regulator type?
Why: A system that recycles gas is closed circuit; its opposite, which vents exhaled air, is open circuit.
4_____ has one of the highest heat capacities of any naturally occurring substance, which is why divers lose body heat quickly.
Why: Water's exceptionally high heat capacity is why it draws heat from the body so effectively.
5Following a single dive at 450 metres/1500 feet of altitude, what minimum surface interval is recommended before boarding a flight?
Why: 12 hours is the minimum recommended preflight surface interval following this single altitude dive.
6Using the rule that pressure increases by roughly 1 atmosphere for every 10 metres/33 feet of sea water, what is the absolute pressure at 34 metres/112 feet?
Why: 34 metres of sea water adds about 3.4 ata, plus 1 ata at the surface, giving a total absolute pressure of about 4.4 ata/64.5 psia.
7Which combination of tasks may be legitimately delegated away from the instructor during the Open Water Diver course, according to standards?
Why: All three delegated tasks together represent the recognized supervision exceptions under standards.
8Lena and her buddy must locate a small lost outboard motor somewhere within a boulder-strewn, patchy reef area measuring 30 metres by 30 metres / 100 feet by 100 feet. Which search pattern suits this best?
Why: For this size and terrain, the expanding square gives systematic, expanding coverage from a central point.
9Dive center owner Raj wants to know the correct testing schedule for his rental cylinders. What should you tell him?
Why: Both testing schedules are governed by local regulations, with visual inspections generally being annual.
10Three days after diving, a friend mentions transient, sharp elbow pain that appeared for a couple of hours then resolved on its own, with no medication taken. He has since been playing tennis frequently. What is the most reasonable explanation?
Why: The timing (three days post-dive) and known strenuous activity make an athletic strain far more plausible than decompression sickness.
11When using the RDP to plan a dive, how is "bottom time" defined?
Why: The RDP defines bottom time as beginning at the start of descent and ending at the start of the direct ascent to the surface.
12Analyzing why divers struggle to localize underwater sounds, an instructor points out that sound reaches both ears almost simultaneously because it travels through the denser medium of water roughly how many times faster than through air?
Why: Sound travels about four times faster in water than in air because water is much denser, which also makes the sound reach both ears at nearly the same time, hindering localization.
13The emergency weight drop dive flexible skill can be conducted at the surface, in water too deep to stand, during ______.
Why: Standards allow emergency weight drop at the surface, in deep water, on any confined or open water dive.
14Instructor Dana reaches her buddy, who is panicking after a rough surface swim in choppy conditions. Dana's first move should be to:
Why: Positive buoyancy is always the immediate priority when helping a panicking diver at the surface.
15Which single test verifies a heat-exposed cylinder is still structurally safe, beyond what a standard visual inspection can determine?
Why: Only a hydrostatic test can confirm the cylinder's pressure-holding integrity after heat exposure.
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These 15 questions are modeled on the Instructor dive-theory and standards exams (you need 75% to pass). They're original questions covering the real topics and difficulty — not the certifying agency's actual test. For unlimited fresh questions, per-topic drills, and full-length mock exams, read the Instructor (IDC) exam guide or create an account for unlimited practice.
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