Scuba Diving Test Questions: 25 Sample PADI Exam Questions & Answers

Whether you are finishing your PADI eLearning Knowledge Reviews at home or sitting on a boat preparing for the PADI Open Water Final Exam, working through realistic scuba diving test questions is the fastest way to lock in the concepts.

Memorizing random answer letters won't help you underwater — or on the exam when a question is phrased slightly differently. Instead, if you understand why each answer works across the five core modules of the Open Water Diver course, you will breeze past the 75% passing mark.

Below are 25 sample scuba diving test questions grouped across all 5 PADI Open Water sections, complete with the correct answer and the exact physics or safety logic behind it. When you finish reading, test yourself interactively on our free PADI Open Water Quiz.

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Module 1: Pressure, Volume, Equalization & Breathing (Questions 1–5)

Every scuba test starts with Boyle's Law: for every 10 metres (33 feet) you descend in seawater, ambient pressure increases by 1 bar / 1 ata.

Question 1: Sealed Balloon Volume at Depth

If you take a sealed flexible bag containing 6 litres of air from the surface down to 20 metres (66 feet), what will its volume be?

• A) 3 litres
• B) 2 litres
• C) 1.5 litres
• D) 18 litres

Correct Answer: B (2 litres). Explanation: At 20 metres, total absolute pressure is 3 bar/ata (2 bar of water + 1 bar of atmospheric pressure). Divide the surface volume (6 L) by 3 = 2 litres.

Question 2: Partially Inflating a Balloon Underwater

You are at 10 metres (33 feet) and put 4 litres of air from your regulator into a flexible lift bag, then seal it. If it rises to the surface without venting, what volume will the air expand to?

• A) 2 litres
• B) 4 litres
• C) 8 litres
• D) 12 litres

Correct Answer: C (8 litres). Explanation: At 10 metres, total pressure is 2 bar/ata. When the sealed bag ascends to the surface (1 bar/ata), the pressure is halved, so the gas volume doubles: 4 L × 2 = 8 litres.

Question 3: Ear Equalization Timing

When descending, how often should you equalize your ears and sinuses?

• A) Every metre (few feet), before you feel discomfort or pain
• B) Only when your ears start hurting
• C) Once at 5 metres and once at 10 metres
• D) Only if you have a cold

Correct Answer: A (Every metre / few feet, before you feel discomfort). Explanation: Waiting until your ears hurt allows pressure to lock the Eustachian tubes shut. If you cannot equalize during descent, stop immediately, ascend slightly until the pressure eases, equalize gently, and continue.

Question 4: The Most Important Rule in Scuba Diving

What is the single most important rule in scuba diving?

• A) Never dive alone
• B) Breathe continuously and never hold your breath
• C) Always do a 3-minute safety stop
• D) Check your SPG every 5 minutes

Correct Answer: B (Breathe continuously and never hold your breath). Explanation: Because compressed air expands as you ascend, holding your breath during even a small upward movement can cause a lung overexpansion injury (arterial gas embolism). Learn more in our Decompression Illness (DCI) guide.

Question 5: Reverse Blocks on Ascent

During ascent, you feel pressure building in your ears or sinuses (a reverse block). What should you do?

• A) Pinch your nose and blow harder while ascending
• B) Stop, descend a metre or two until the pain stops, and give the trapped air time to work its way out slowly
• C) Inflate your BCD to reach the surface quickly
• D) Take your regulator out and swallow water

Correct Answer: B. Explanation: Never pinch your nose and blow (Valsalva) on ascent — that pushes more air into an already over-pressurized space. Descending slightly shrinks the trapped air and relieves pain so it can vent naturally.

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Module 2: Buoyancy, Weighting, Exposure Suits & Underwater Vision (Questions 6–10)

Question 6: Saltwater vs. Freshwater Buoyancy

You are properly weighted in the ocean (saltwater) wearing the exact same wetsuit and tank. If you move to a freshwater lake, how will you need to adjust your weight belt?

• A) Add weight
• B) Remove weight
• C) Keep the exact same weight
• D) Switch to an aluminum tank

Correct Answer: B (Remove weight). Explanation: Saltwater contains dissolved minerals and is denser than freshwater, meaning saltwater pushes you up more strongly. In less-dense freshwater you float less, so you need less lead weight to sink.

Question 7: Performing a Proper Weight Check

At the surface with an empty BCD, if you are properly weighted and hold a normal breath, where should you float?

• A) At eye level, and sink slowly when you exhale
• B) With your shoulders above water
• C) Completely submerged at 1 metre
• D) At chin level with a half-inflated BCD

Correct Answer: A (At eye level, sinking slowly when you exhale). Explanation: And remember to add around 2 kg (5 lbs) extra if you are doing the check with a full cylinder at the start of the dive, so you can still hold your 5-metre safety stop when your tank is nearly empty at the end of the dive.

Question 8: Wetsuit Compression at Depth

What happens to a neoprene wetsuit's buoyancy and warmth as you descend deeper?

• A) It becomes more buoyant and warmer
• B) Water pressure compresses the gas bubbles in the neoprene, making the suit thinner, less buoyant, and less warm
• C) Buoyancy changes, but thermal insulation stays identical
• D) It absorbs air from your BCD

Correct Answer: B. Explanation: To compensate for wetsuit compression as you go deeper, you add small bursts of air to your BCD to maintain neutral buoyancy.

Question 9: Underwater Magnification

Because light refracts through your mask lens and air space, how do objects appear underwater?

• A) About 33% larger and 25% closer than they really are
• B) About 50% smaller and farther away
• C) Exactly true to size
• D) Narrower and further away

Correct Answer: A (About 33% larger / 4:3 ratio and 25% closer). Explanation: Refraction makes things look roughly one-third bigger and one-quarter closer.

Question 10: Efficient Breathing Pattern Underwater

Which breathing pattern is most efficient for scuba diving and helps prevent airway restriction at depth?

• A) Quick, shallow breaths
• B) Slow, deep breaths
• C) Skip-breathing (holding each breath for 5 seconds)
• D) Rapid exhalations followed by short inhales

Correct Answer: B (Slow, deep breaths). Explanation: Denser air at depth creates more turbulence in your regulator and airways. Slow, deep breathing minimizes dead-space gas exchange and prevents carbon dioxide buildup. NEVER skip-breathe.

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Module 3: Air Consumption, Currents & Emergency Procedures (Questions 11–15)

Question 11: Air Consumption Math at Depth

If a diver consumes 20 bar of air in 10 minutes at the surface, how much air will they consume in 10 minutes at 20 metres (66 feet), assuming the same breathing rate?

• A) 40 bar
• B) 60 bar
• C) 80 bar
• D) 20 bar

Correct Answer: B (60 bar). Explanation: At 20 metres, ambient pressure is 3 bar/ata (3 times surface pressure). Therefore, every breath takes 3 times as many air molecules from the cylinder: 20 bar × 3 = 60 bar. See our guide on how long you can stay underwater scuba diving for more examples.

Question 12: Swimming Against a Current

At the start of a boat dive, which direction should you generally begin swimming if a mild current is present?

• A) With the current, so you have to swim against it when low on air
• B) Into (against) the current, so the current helps push you back to the boat at the end of the dive
• C) Straight down to the deepest possible point
• D) Diagonally away from the reef

Correct Answer: B (Into the current). Explanation: Beginning your dive into the current means that when you are tired and down to your reserve gas, you can drift effortlessly back to the ascent line. If caught in a sudden strong current mid-water, swim across (perpendicular to) the current or stay close to the bottom/reef where water movement is slower.

Question 13: Free-Flowing Regulator

If your primary second-stage regulator begins free-flowing continuously underwater, what should you do?

• A) Hold your breath and bolt to the surface
• B) Do not seal your lips around the mouthpiece; hold it slightly out of your mouth, "sip" air from the escaping stream, and ascend safely
• C) Turn off your tank valve yourself
• D) Switch to your snorkel underwater

Correct Answer: B. Explanation: Sealing your lips around a free-flowing regulator can over-pressurize your lungs. Letting the excess air spill past your cheek while sipping from the bubble stream allows a calm, normal ascent.

Question 14: Out-of-Air Situations — Best Option

You accidentally run completely out of air at 12 metres and your buddy is right next to you. What is your best option?

• A) Controlled Emergency Swimming Ascent (CESA)
• B) Ascend using your buddy's alternate air source (octopus)
• C) Buoyant Emergency Ascent (dropping your weights)
• D) Share a single regulator by passing it back and forth

Correct Answer: B (Use your buddy's alternate air source). Explanation: When your buddy is close, linking up and ascending on their alternate air source is always the safest primary response. If your buddy is too far away and you are within 6–9 metres (20–30 feet) of the surface, use a Controlled Emergency Swimming Ascent (CESA) while making a continuous "aaah" sound.

Question 15: Pre-Dive Safety Check (BWRAF)

What do the five steps of the PADI pre-dive buddy check (BWRAF) stand for?

• A) Boats, Waves, Reefs, Air, Fins
• B) BCD, Weights, Releases, Air, Final OK
• C) Buoyancy, Wetsuit, Regulator, Alternate, Fins
• D) Buddy, Watch, Regulator, Air, Float

Correct Answer: B (BCD, Weights, Releases, Air, Final OK). Explanation: Many divers remember this with the mnemonic "Begin With Review And Friend" or "Bruce Willis Ruins All Films."

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Module 4: Dive Computers, No-Stop Limits & Decompression Sickness (Questions 16–20)

Question 16: Sharing Dive Computers

Can two buddy divers who stay together for the entire dive share a single dive computer?

• A) Yes, as long as they stay within 2 metres of each other
• B) No — every diver must wear their own dive computer
• C) Yes, on the first dive of the day only
• D) Yes, if they stay shallower than 18 metres

Correct Answer: B (No — every diver must have their own computer). Explanation: Even buddies who swim side by side have slight differences in depth and ascent rates, and if buddies ever get separated, a diver without a computer has no depth gauge, timer, or ascent-rate monitor.

Question 17: No-Stop (No-Decompression) Limits

What happens to your allowable no-stop time as you dive deeper?

• A) It gets shorter
• B) It gets longer
• C) It stays the same up to 30 metres
• D) It resets every 10 minutes

Correct Answer: A (It gets shorter). Explanation: Higher ambient pressure drives nitrogen into your tissues faster, reducing the time you can stay before mandatory decompression stops would be required.

Question 18: Planning Repetitive Dives

When planning two or more dives in a single day, which dive should be the deepest?

• A) The last dive of the day
• B) The first dive of the day, with each subsequent dive shallower than the previous one
• C) Depth order does not matter if you use a computer
• D) Alternate shallow, deep, shallow

Correct Answer: B (First dive deepest, subsequent dives shallower). Explanation: Performing your deepest dive first when your tissues have the lowest residual nitrogen maximizes bottom time and minimizes decompression stress.

Question 19: Flying After Diving Rules

According to DAN and PADI guidelines, what is the minimum pre-flight surface interval after completing multiple dives (or multi-day diving) with no decompression stops?

• A) 6 hours
• B) 12 hours
• C) 18 hours
• D) 24 hours

Correct Answer: C (18 hours). Explanation: Standard guidelines recommend a minimum of 12 hours after a single no-stop dive, and 18 hours after repetitive dives or multiple days of diving, because commercial aircraft cabins are pressurized to the equivalent of ~2,400 m (8,000 ft) altitude.

Question 20: First Aid for Suspected Decompression Illness (DCI)

What is the primary first-aid treatment for a diver showing signs or symptoms of Decompression Sickness (DCS) or Lung Overexpansion Injury?

• A) Put the diver back underwater to recompress them
• B) Provide 100% emergency oxygen, keep the diver lying down, monitor ABCs, and contact emergency medical services / DAN
• C) Have the diver run around to increase circulation
• D) Give the diver painkillers and wait 12 hours

Correct Answer: B. Explanation: Never attempt in-water recompression. Administer 100% oxygen immediately and arrange transport to a hyperbaric chamber.

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Module 5: Dive Planning, Compass Navigation & Gas Hazards (Questions 21–25)

Question 21: Underwater Compass Reciprocal Heading

You are navigating out along a reef on a compass heading of 90 degrees. To return along the exact reciprocal course, how should you set your compass bezel and lubber line?

• A) Turn 180 degrees until your index marks straddle the north needle in the opposite direction (270 degrees), keeping the lubber line pointed straight ahead of your body
• B) Hold the compass sideways
• C) Add 90 degrees to your bezel
• D) Follow the white end of the needle

Correct Answer: A. Explanation: Always keep the lubber line aligned with the centerline of your body/travel direction, and rotate your body until the north needle sits opposite its outbound position.

Question 22: Contaminated Air Symptoms

You notice your scuba tank air has an oily taste or odor, or you develop a headache and nausea during a dive. What should you suspect?

• A) Nitrogen narcosis
• B) Contaminated air (such as carbon monoxide from a faulty compressor)
• C) Oxygen toxicity
• D) Sea sickness only

Correct Answer: B (Contaminated air). Explanation: Compressed air should be completely odorless and tasteless. Never dive a cylinder that smells or tastes of oil or exhaust; abort the dive safely and report the fill to the dive center.

Question 23: Gas Narcosis (Nitrogen Narcosis)

If a diver experiences symptoms of gas narcosis (poor judgment, euphoria, or anxiety) at 30 metres, what is the immediate cure?

• A) Breathe faster
• B) Ascend to a shallower depth until symptoms disappear
• C) Inflate the BCD fully
• D) Wait 5 minutes at the same depth to adapt

Correct Answer: B (Ascend to a shallower depth). Explanation: Gas narcosis is caused by elevated partial pressure of nitrogen at depth and clears almost immediately as soon as you ascend a few metres.

Question 24: Safety Stop Depth and Time

Where and for how long is a standard recreational safety stop performed?

• A) 3 metres for 1 minute
• B) 5 metres (15 feet) for 3 minutes
• C) 10 metres for 5 minutes
• D) 6 metres for 10 minutes

Correct Answer: B (5 metres / 15 feet for 3 minutes). Explanation: Pausing at 5 metres for 3 minutes at the end of every dive slows your ascent through the greatest pressure-change zone (the last 5 metres to the surface) and allows extra nitrogen off-gassing.

Question 25: Maximum Depth Limit for Open Water Divers

What is the maximum recommended depth limit for a newly certified PADI Open Water Diver (age 15+)?

• A) 12 metres (40 feet)
• B) 18 metres (60 feet)
• C) 30 metres (100 feet)
• D) 40 metres (130 feet)

Correct Answer: B (18 metres / 60 feet). Explanation: Junior Open Water Divers aged 10–11 are limited to 12 metres (40 feet); Open Water Divers aged 12+ are limited to 18 metres (60 feet). Reaching 30 metres (100 feet) requires the Advanced Open Water Diver certification. Read more in our guide on how deep you can scuba dive.

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Next Steps: Take the Full Interactive Quiz

If you got at least 19 out of 25 right (76%), you are already above the PADI passing threshold. To prepare for the remaining topics — including hand signals, boat procedures, cold-water hypothermia, and aquatic life injuries — read our PADI Open Water Exam & Final Assessment guide, check our PADI Open Water Swim Test guide, and launch the full interactive PADI Open Water Practice Quiz.