Scuba Diving Cheat Sheet 2026

The 30 highest-yield Scuba Diving facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. What does the term 'kick cycle' refer to in underwater navigation? → A unit used to estimate distance traveled underwater
2. What is a delayed surface marker buoy (DSMB)? → A marker buoy deployed underwater before surfacing
3. What should a diver do if stung by a jellyfish underwater? → Move away calmly, alert the buddy, and treat the sting after surfacing
4. When navigating a square pattern underwater, what degree turn is made at each corner? → 90 degrees
5. Why should the deepest dive of the day be planned first? → To minimize residual nitrogen for subsequent shallower dives
6. During a dive, a diver notices their ears feel full and painful at 15 feet. This is most likely caused by: → Failure to equalize the middle ear against increasing water pressure
7. How frequently should you visually inspect your scuba tank? → At least once a year, more frequently if used often
8. An arterial gas embolism (AGE) is most commonly caused by which diving action? → Holding the breath while ascending
9. Dalton's Law of partial pressures states that the total pressure of a gas mixture equals: → The sum of the partial pressures of each individual gas
10. What is the primary function of a regulator in scuba diving? → Reduce tank pressure to breathable levels
11. Which type of fin style allows divers to wear thick booties and provides more thrust? → Open-heel fins
12. True or false: I can become a safer diver and a better buddy by getting more training. → True
13. What is the function of the second stage in a two-stage scuba regulator system? → Deliver air at ambient pressure directly to the diver's mouth
14. What is 'total bottom time' (TBT) in repetitive dive planning? → Residual nitrogen time plus actual bottom time of the current dive
15. Which gas law explains why a diver's lungs could rupture if they hold their breath while ascending? → Boyle's Law
16. When planning a drift dive, where should the diver typically exit the water? → Downstream from the entry point, at a pre-planned exit
17. What is the most frequent injury associated with diving? → Ear injuries
18. Why is it important to rinse scuba equipment with fresh water after a dive? → Remove salt, sand, and debris that cause corrosion
19. You want to be _________ when you've descended to your desired depth. → neutral buoyancy
20. What is the recommended minimum tank pressure at which a diver should begin their ascent? → 500 PSI (35 bar)
21. What is the correct action when a diver accidentally breaks a piece of coral? → Leave it in place, report the incident, and do not attempt to reattach it
22. What is the purpose of a scuba mask purge valve? → Clear water from the mask without removing it
23. What is a 'multi-level dive' in the context of dive planning? → A dive that moves from deeper to shallower depths, extending bottom time
24. What is 'piloting' as a navigation technique in scuba diving? → Moving from one known landmark to the next in sequence
25. The diver's ____ is also known as the cylinder. → tank
26. What is 'nitrogen narcosis' and at what depth does it typically begin to affect recreational divers? → Impaired judgment from dissolved nitrogen, typically below 100 feet (30 meters)
27. What is the recommended maximum ascent rate in recreational scuba diving? → 30 feet (9 meters) per minute or slower
28. What is a no-decompression limit (NDL) in recreational scuba diving? → Maximum time at a given depth before a decompression stop is required
29. What is an 'emergency action plan' (EAP) in the context of scuba diving? → A pre-established set of steps and contacts to follow if a diving emergency occurs
30. What certification is required before a US diver can fill a nitrox tank? → Enriched Air Nitrox specialty certification from a recognized training agency