PADI Open Water Diver course

A depth change of 10 metres/33 feet causes a pressure change of ...

1 bar/ata

What are my four breathing rules as a scuba diver?

1. Breathe continuously and never, ever, hold your breath. 2. Breathe slowly and deeply. 3. Do not allow yourself to get winded or out of breath. 4. If faced with a problem, stop, then reduce anxiety by maintaining or restoring slow, deep breathing.

What are five things I can do before the end of the course to help me continue to enjoy and be involved with diving after certification?

1. Join and participate in your local dive center's dive club and/or social events, and log onto PADI Club® to connect with other divers. 2. Enroll in a PADI specialty course, such as underwater photography or wreck diving, after successfully completing your PADI Open Water Diver certification. 3. Start courses like PADI Dry Suit Diver and PADI Enriched Air Diver during your PADI Open Water Diver course. 4. Sign up for a dive trip involving travel or plan a local dive to further immerse yourself in the diving lifestyle. 5. Invest in your first scuba equipment, including a regulator, BCD, dive computer, and/or wet suit or dry suit, to enhance your diving experience.

What are three overall benefits of the buddy system?

1. Practicality - you assist each other before, during and after the dive. 2. Safety - you help each other prevent problems, and you assist each other if there is an emergency. 3. Fun - diving is a social activity; it's rewarding and fun to have someone to share underwater adventures.

How can I learn most effectively during Knowledge Development and the Confined Water and Open Water Dives?

1. Scan the section contents, generally noting headings, topics, pictures and so on. Focus on what you're going to read immediately more thoroughly. 2. Read the learning objectives for each subsection, then read the subsection. Look for the answers to each question; when you find an answer, note it on a pad. 3. Answer the exercise questions at the end of each subsection. These are not tests, and the answers are right there. They're simple and quick. If you missed one, review the material until you understand. If you still don't get it, be sure to ask your instructor. 4. Watch the video. The video reinforces the concepts you've learned. It also shows the details for some of the skills you'll practice. 5. Answer the knowledge reviews at the end of each section. If you don't know something, review the information and then answer. If you still don't understand, ask your instructor. 6. Complete the assigned independent study before each session. Your instructor will let you know what to complete, by when, so you can schedule the time you need and take it seriously. If you need a different schedule, let your instructor know so you can come up with one that works together. 7. Get your instructor's help. When you meet, your instructor will discuss any areas in which you had difficulties and ask questions. 8. Complete the section quiz and final exam. You will complete a quiz for each of the first four sections, and a comprehensive final exam after Section Five. Before each, take a moment to review each section and your notes.

If you take 6 litres of air from the surface to 20 metres/66 feet, the volume will be _____ litres.

2 litres (1/3 of 6 litres)

How do I prepare a new mask for diving?

A new mask needs some preparation. You may need to scrub the interior of the glass with a mask cleaner made for this purpose. This removes protective chemicals that some manufacturers apply. These chemicals increase a mask's tendency to fog. Other than that, your main preparation is to adjust the strap. Fit it over the crown of your head, above your ears, with a snug but not overly tight fit. Secure the strap-locking device if it has one. Many masks allow you to put them on slightly loose, then tighten for a perfect fit.

What is a "reverse block"?

A reverse block (also called a reverse squeeze) results when expanding air becomes trapped in a body air space. Reverse blocks can result from using a decongestant to dive with a cold or allergy. During the dive, the decongestant can wear off and the congestion can trap air in the ears and/or sinuses. (Don't dive with cold/allergy congestion, even with medications). To avoid discomfort during ascent caused by gas forming in the stomach/intestines, refrain from consuming gas-producing foods before diving and avoid swallowing air while underwater. Additionally, rare occurrences like tooth squeezes or reverse tooth squeezes may happen. If you encounter issues, especially with air seeping into dental fillings during a dive, consult your dentist promptly.

Why do I need a snorkel?

A snorkel is essential at the surface to conserve air while your face is in the water, particularly in choppy conditions or when waves are splashing. It facilitates easier breathing and conserves air when looking underwater or swimming with your face submerged, reducing fatigue compared to lifting your head repeatedly to breathe. The snorkel becomes even more crucial if you have limited air left and need to swim a considerable distance to the boat or shore or wait in the water while other divers exit.

How do I prepare my BCD for use?

Adjust your BCD for a snug, not overly tight fit, ideally while wearing your exposure suit. Fully inflate the BCD to ensure it doesn't restrict breathing. Attach a whistle near the low-pressure inflator for easy access and hose retainers for regulator components as needed.

What are 11 reasons to dive?

Adventuring and exploring. Enjoying and observing nature. Spending time with friends/family. Getting out on and under the water. Taking photos and videos. Investigating sunken ships. Taking on personal challenges. Becoming familiar with new technologies. Making new friends. Making a difference in environmental issues. Enjoying a new world.

What four equipment systems combine to make my scuba kit (scuba unit), and what is the purpose of each?

BCD (Buoyancy Control Device) - Holds your kit together and allows you to adjust buoyancy throughout the dive. Regulator - Delivers breathing air at the surrounding pressure when you inhale and directs exhaled air into the water. Cylinder - Holds the high-pressure breathing air supplied by your regulator during the dive. Weight system - Holds lead weight to counteract the positive buoyancy of your body and some of your equipment, with a mechanism for dropping some or all the weight in an emergency.

How does depth affect how long my air supply lasts?

Because scuba provides air at the surrounding pressure, as you go deeper each breath takes more air from your scuba cylinder. Therefore, the deeper you are, the faster you use your air. How fast you use your air follows the pressure/volume relationship: - Your air supply lasts ½ as long at 10 metres/33 feet (2 bar/ata) than at the surface (1 bar/ata). - Your air supply lasts 1/3 as long at 20 metres/66 feet (3 bar/ata) than at the surface (1 bar/ata), ¼ at 30 metres/99 feet and so on

Why does my mask need to enclose my nose?

Because the mask creates an air space, you need your nose to blow in it to equalize it

What is the most important rule in scuba diving?

Breathe continuously and never hold your breath. Because scuba supplies air at the surrounding pressure, your lungs are at normal volume at depth. When ascending, the air in your lungs expands, but this is not a problem when you breathe normally. Your lungs stay at their normal volume because you release expanding air with each exhalation.

What causes buoyancy?

Buoyancy cancels the pull of gravity, allowing you to "fly" and feel "weightless." Buoyancy is an upward force acting on an object in water, which is why you feel "lighter" in water. This force is caused by the water displaced (pushed aside) by the object, and is equal to the weight of the water displaced. There are three types of buoyancy

What considerations and options do I have when choosing a BCD?

Buoyancy capacity - Most BCDs cover a wide range of diving circumstances. Your BCD should have ample buoyancy to easily float you and all your equipment at the surface. You sometimes hear the amount of buoyancy called "lift" capacity. Pockets and D-rings - Many BCDs have pockets for storing and D-rings for attaching accessories. Shoulder quick release - A quick-release buckle on one or both shoulders makes it easier to get out of your kit. Colors and style - Choose a look that matches the rest of your gear.

What does certification in this course mean?

Certification shows that you met the course requirements. Dive centers and resorts require proof of certification before they will rent scuba equipment or fill scuba cylinders. As a term-4PADI Open Water Diver, you will be trained to a maximum depth of 18 metres/60 feet (or the actual depth you reached, if shallower). As a PADI Scuba Diver, you may also dive under PADI Instructor or PADI Divemaster supervision as deep as 12 metres/40 feet.

What are my considerations and options when choosing an SPG?

Considerations for your SPG are influenced by your choice of a dive computer. For non-air-integrated computers, a standard mechanical SPG is usually chosen, either independent or combined with other instruments in a console, secured to the left side of your BCD. If your SPG is part of an air-integrated computer on a hose, it secures similarly and may be part of a console with additional instruments. For hoseless computers on your wrist, receiving air supply information wirelessly, some manufacturers recommend having a separate conventional SPG, even with air-integrated computers. SPGs offer reliable service with proper care, and accuracy should be checked if it doesn't read zero when unpressurized or if any concerns arise.

What are four secondary considerations when choosing scuba equipment?

Cost and features - You can choose gear from a price range, with more features on higher-end models. Serviceability - Consider that some equipment requires annual or biannual professional servicing. Most dive operations service the brands they sell, so getting gear from your PADI dive shop typically covers this. Color and style - You can choose gear that looks good and is color-coordinated. Accessories - For each piece of equipment, your PADI Professional can suggest related accessories. A professional at your PADI dive shop may, for example, suggest retainers that hold equipment where it belongs, or an appropriate mask defog so you see clearly. These contribute significantly to diving comfort and convenience. Don't neglect useful accessories.

What three safety precautions for handling scuba cylinders should I follow?

Cylinders are heavy, so there are three main handling precautions to follow. Don't leave a cylinder standing unattended, particularly once you assemble your scuba kit. A falling cylinder can damage equipment and injure people. Lay it down with the BCD up. Secure cylinders for transportation. Block or otherwise restrain them securely so they can't roll or slide. Keep cylinders secured on boats. Cylinders can tumble from their racks when the boat rocks, posing an injury risk as well as possibly damaging gear and the boat. Have a restraining cord in place (if the cylinder rack has one), even if you step away only momentarily.

What six special maintenance considerations do cylinders have?

Cylinders, when cared for properly, can last for decades. They require six special maintenance steps: 1. Periodic hydrostatic tests every two to five years, as mandated by laws and regulations. Check the stamped date on the cylinder for the last test, and have it conducted by your PADI dive operation. 2. Annual visual inspections, where cylinders are drained, opened, and internally checked for corrosion or damage. - Never fill a cylinder without a current inspection sticker, obtainable from your PADI Dive Center. 3. Open and close the valve gently to avoid damage. 4. Keep some air (around 20 bar/300 psi) in the cylinder to prevent moisture entry; if accidentally drained, seek a visual inspection. 5. Store the cylinder upright in a secure location to allow moisture accumulation at the bottom, the thickest part. 6. Avoid exposing the cylinder to high heat, which can increase air pressure, damage the alloy, or lead to burst disk issues. In case of a fire, professional testing is necessary before reuse, especially for aluminum cylinders.

In an emergency, is it necessary to drop all my weight?

Depending on the type of exposure suit you're wearing, you may need to drop only part of your weights (for full wet suits or dry suits) or all of your weight (for no exposure suit or partial wet suits) to achieve proper buoyancy.

What is a sidemount?

Divers have worn scuba cylinders on their backs for decades - but there's a "newer" option: sidemount. In sidemount, you wear at least one, but usually two, cylinders on your sides instead of your back. Despite its unconventional appearance, a well-designed sidemount setup is streamlined and comfortable. It offers benefits such as ease of transport, suitability for individuals with lower-back issues, and enhanced safety for air supply emergencies.

How does getting my PADI Dive Center or Resort to help me with my equipment help me learn to dive and enjoy diving better?

Diving requires essential equipment, and choosing the right gear is crucial for comfort and optimal function. While it's impossible for a course to cover all equipment features, your local PADI Dive Center or Resort professionals can assist in selecting gear based on your preferences, budget, and diving goals. Proper fit is key for comfort and distraction-free learning, and professional guidance ensures the best choices. Ideally, dive in your own gear chosen with expert help, enhancing both your course experience and enjoyment as a certified PADI Open Water Diver.

What is the purpose of Confined Water Dives (step 2)?

During the Confined Water Dives, you learn and practice scuba skills in a pool or water with pool-like conditions under direct instructor supervision. You also practice applying what you learn in Knowledge Development.

What is "equalization" and how do I equalize as I descend?

Equalization is the process of adding air to the air spaces as you descend. This keeps their pressure equal with the outside pressure, so they stay at their normal volume. This is called equalization. To equalize your ears and sinuses, pinch your nose and blow gently against it. This sends air from your throat into your ears and sinuses. Some people find that wiggling their jaws side to side and swallowing also works. To equalize your mask, blow air into it through your nose as you descend. This is why you can't use goggles for scuba diving - they don't enclose your nose, so you can't equalize them.

How often should I equalize?

Equalize every metre/few feet, before you feel discomfort. If you wait until you feel discomfort, equalization may be difficult or impossible. When you equalize as often as you should, you don't feel discomfort or pain.

Why should I equalize gently?

Equalize gently. Never attempt a forceful and/or extended equalization. A forceful, extended equalization can cause serious permanent injuries to your ears and hearing. Use short, frequent, gentle equalizations. If short, frequent, gentle equalizations don't work, stop your descent, signal your buddy(ies)/instructor, ascend until the discomfort passes and try again. With practice, equalizing becomes easier for most people.

Why do I need fins?

Fins provide a large surface area for your powerful leg muscles to push against so you move efficiently through water.

What five components make up a regulator, and what does each do?

First stage: The regulator's first stage is the central hub connecting to the cylinder valve through screwing or a yoke system, reducing cylinder pressure to an intermediate pressure, usually 7-10 bar/100-150 psi above the surrounding pressure. Second stage: Delivering air on demand, the second stage operates with a flexible diaphragm, featuring one-way valves for exhalation and a purge button for manual air release. Alternate air source: An extra second stage for sharing air, commonly a standard second stage on a longer hose, or an alternate inflator regulator. Pony bottles or self-contained ascent bottles are smaller cylinders for independent or shared use. Low-pressure inflator hose: Supplies air to the BCD inflator, with two hoses when diving with a dry suit, allowing you to add air as you descend. SPG/computer: Displays remaining air pressure in the cylinder through a hose with a mechanical gauge reading in bar or psi. It can be part of a console or integrated into a dive computer, with hoseless air-integrated computers using a transmitter to relay data from the first stage.

What is the pressure change for each 10 metres/33 feet of depth change?

For every 10 meters (33 feet) you descend, the pressure increases by one bar or atmosphere (ata), and conversely, it decreases by one bar/ata for every 10 meters/33 feet you ascend.

What features should I consider when choosing a snorkel?

Get a snorkel made specifically for divers so it has the features you need. Adjust it to fit comfortably in your mouth with the top at the crown of your head. Optional features and considerations include: Flexible lower portion - Allows the snorkel mouthpiece to drop out of the way when not in use. Self-drain valve - Makes it easier to blow water out of the snorkel. Splash guard - Reduces the amount of water than can splash in during use. Color - You can match your other gear, though some divers like a bright color that's easy to see.

What can happen if I don't follow the most important rule in scuba diving?

If during ascent you were to hold your breath, blocking your airway, your lungs would over expand. They would be much like a balloon filled and sealed at depth, which expanding air would burst during ascent. Even slight pressure changes - as little as 1 metre/2-3 feet - can cause these injuries if you were to ascend holding a full breath. Lung overexpansion injuries are difficult to treat and can cause paralysis and death by forcing air into the bloodstream and chest cavities. Treatment usually requires recompression (being put back under pressure) in a chamber as soon as possible. However, diving commonly takes place several hours (or more) from a recompression chamber. This rule is so important, that any time your regulator is not in your mouth you exhale a slow, steady bubble stream so you aren't holding your breath. Also, do not dive with lung congestion, which can trap air in the lungs and cause overexpansion injuries.

What should I do if I can't equalize? What can happen if I don't or can't equalize and keep descending?

If you can't equalize, stop your descent immediately. Signal your buddy(ies) or instructor - they have no way of knowing you have an equalization problem unless you tell them. Signal "problem" and point to your ear (you'll learn these and other hand signals later in this section). Ascend slightly until the discomfort passes and try again. Be patient. After you equalize, descend more slowly, equalizing more frequently.If you still can't equalize, stop the dive. Continuing to descend with unequalized air spaces can lead to serious injuries. Ear injuries include fluid accumulating in the middle ear, and eardrum rupture. Eardrum rupture underwater can cause severe vertigo (dizziness and loss of balance), and requires medical treatment. An unequalized mask can cause bruising around your eyes. While it's usually not serious and clears with time, its appearance is dramatic and may be alarming.A physician should check serious squeezes to avoid long-term injury and complications.

What is a "squeeze"?

If you don't adjust for increasing pressure compressing a body air space, you can get a squeeze. A squeeze causes discomfort and, if not corrected, can cause injury by pressure imbalance that pushes tissues into an air space. This happens because there is greater pressure outside the air space than inside it. Discomfort in the ears as you descend is from an ear squeeze. It is caused by pressure pushing your eardrum and surrounding tissues inward (a pressure imbalance between the surrounding pressure and an air space.) . A pulling or sucking sensation on your face is from a mask squeeze. Discomfort in your cheeks, central forehead and along the nose is from a sinus squeeze. Other squeezes are possible, but not common.

What should I do if I feel discomfort in my ears, sinuses, stomach, intestines or teeth while ascending?

If you feel discomfort in any air space during ascent, immediately slow or stop your ascent. Descend a metre/few feet to reduce the discomfort and give the trapped air time to work its way out. Ascend more slowly, giving the expanding gas time to exit. If you have severe or frequent reverse blocks, see a physician knowledgeable in dive medicine.

What other body air spaces are affected by increasing pressure? How do I equalize them?

Increasing pressure may affect other body air spaces as you descend: - Filled teeth (If it happens, stop your descent because you can't equalize this air space.) - The dry suit (It holds a layer of air around your body during the dive. Increasing pressure compresses this air, but you learn to equalize this space in the PADI Dry Suit Diver course. - Lungs (you don't need to do anything special to equalize your lungs other than to breathe normally and continuously. When skin diving (breath-hold diving), your lungs compress as you descend, but they are designed to do this. The only possible concerns are if you were to descend after exhaling completely, or if you were to breath-hold dive, very deep (60 metres/200 feet or more). These are unlikely for most divers.)

What five components make up a BCD, and what does each do?

Inflatable Bladder: A durable bag for buoyancy control. Cylinder Band and Harness/Jacket: Adjustable harness integrating with the bladder, with options for different configurations. LPI (Low Pressure Inflator) Mechanism: Inflates the bladder with air from the cylinder via the regulator. Overpressure/Quick Exhaust Valves: Automatically vent excess air and may have manual "quick dump" valves for manual air release. Weight System: Many BCDs feature weight pockets for emergency release, especially useful with added weight, like when wearing a dry suit.

How do I generally care for scuba equipment?

Inspect: Before each use, check for proper operation, wear, and damage. Replace worn parts, like mask or fin straps, and consult professionals for major issues, such as regulator problems. Rinse and Dry: After use in different waters, rinse thoroughly with clean water. Allow drying out of direct sunlight before storing in a cool, dry place to ensure reliability and longevity. Prevent Sun Exposure: Avoid prolonged exposure to direct sunlight and cover your kit between dives to prevent color fading and material deterioration. Professional Servicing: Some items require periodic professional inspection, overhaul, or adjustment. Follow manufacturer specifications and have items serviced regularly. Manufacturer's Guidelines: Adhere to maintenance requirements specified by the manufacturer, consulting their literature or website for guidance.

Why is it important to master buoyancy control?

It affects almost everything you do in and under water. Buoyancy control allows you to: - Descend and ascend at a slow, controlled rate. - Stop a descent or ascent and maintain your depth with little effort. - Float comfortably on the surface. - Save energy and avoid harming sensitive aquatic organisms by swimming neutrally buoyant and controlling your movements. - Maintain the underwater visibility by helping you not stir up the bottom. - Enjoy one of the sensations unique to diving - "weightlessness."

What benefits are there to choosing the components of my scuba kit as an integrated package.

It's a good strategy to choose integrated packages rather than individual items. Choose equipment based on the type of dives you plan to make and how it fits in with equipment you have, or will have. 1. Mask, fins and snorkel. You can have a lot of fun with just these. Don't forget mask defog, wet suit boots for open-heel fins, spare straps and a mesh carrying bag. 2. Regulator (with alternate air source, submersible pressure gauge and dive computer), BCD, weight system, cylinder - your scuba kit. Don't forget an equipment bag, hose protectors, clips and accessories for rigging, spare o-rings, etc. 3. Exposure suit, exposure suit accessories, BCD. The BCD appears here because if you're looking at cooler water diving, you may need a BCD with greater buoyancy and/or higher weight system capacity. Don't forget a mesh bag for carrying a wet exposure suit, suit repair cement, wet suit detergent, and plastic hangers.

What is the purpose of Knowledge Development (step 1)?

Knowledge Development covers the principles, concepts and terms that you need to know for safety and so you can enjoy diving. Short exercises, quizzes and knowledge reviews help you assess and confirm learning as you go.

What should I consider when choosing my scuba kit?

Most scuba kit components require regular professional servicing and inspection; consider this when choosing your gear.

How do I breathe to reduce anxiety when under stress?

My body responds to anxiety with increased breathing, but slow breathing helps reduce anxiety.

Why does congestion from a cold or allergy temporarily keep me from diving? Why should I never dive with earplugs?

Never dive with a cold or allergy. They can cause congestion that might block normal air flow and may make equalization of body air passages difficult or impossible. Using cold medications is not recommended. They can wear off during a dive, and can cause equalization problems as you ascend (more about this shortly). You never use earplugs while diving. They create air spaces that you can't equalize (the exceptions are special ear protectors made specifically for diving). Similarly, a wet suit hood that seals too tightly against an ear can act like an earplug. If so, pull the hood away from your ear momentarily.

What do "performance-based learning" and "student-centered learning" mean? How do they relate to taking PADI courses?

PADI courses apply performance-based learning, which means you progress and attain certification by demonstrating that you meet specific learning objectives. Student-centered learning means that the course, materials and your instructor address how you learn most effectively. Through their design, PADI courses accommodate these differences by allowing students to apply their strengths to offset physical and/or intellectual challenges. This makes diving accessible to a wide range of people without compromising safe diving practices, confidence or comfort. If a suggested technique doesn't work because of your personal situation, ask your instructor to help you adapt the technique, or develop a new one, to meet the requirement some other way.

Where do I place or secure each regulator component when diving? Why is this important?

Primary Second Stage (Breathing Regulator): Placement: Over your right shoulder (under for some models). Importance: It is not secured because it is typically in your mouth during the dive. Alternate Air Source Second Stage: Attachment: Use a quick release in the triangle area. Importance: Proper placement and secure fastening allow your buddy to locate it quickly if needed for sharing air. Brightly colored models are often chosen for better visibility. Submersible Pressure Gauge (SPG): Routing: Under your left arm, securing it with a clip or hose retainer. Importance: Avoid letting it dangle to prevent damage, reduce energy wastage, and ensure easy readability. These placements and securements are crucial for several reasons: Accessibility: Ensures quick and easy access to the alternate air source and SPG, especially in emergency situations. Prevents Damage: Avoiding dangling components prevents damage to the equipment and minimizes the risk of entanglement. Energy Efficiency: Properly securing hoses and gauges reduces drag, promoting energy efficiency during the dive.

What are the requirements for taking the course and for earning my certification?

Prior to the start of the course, you must be at least 10 years old. To be a scuba diver, you need adequate swimming skills. Prior to your second open water dive, you will demonstrate that you can float or tread water without aids for 10 minutes, and prior to certification, that you can swim 200 metres/yards with no aids, or 300 metres/yards with mask, fins and snorkel. You don't need to be an athlete to dive, but you do need good physical health. A few medical conditions can be hazardous while diving. Also, like any active recreation, diving can be physically demanding, so individuals who may be predisposed to heart attack or cardiovascular disease need to exercise caution. As a prudent precaution, before any inwater training, you'll complete a Diver Medical form that screens for conditions that a physician should evaluate. For your safety, respond to all statements honestly and completely. - If you answer "yes" to any condition, you may need to respond to additional statements about the condition, and may need a physician to approve you for diving prior to any inwater training. - In some areas, local law requires a medical exam and a physician's signature in all cases. - If you don't yet have a medical form, you can download it from padi.com.

How do I prepare my regulator for use?

Professional Attachment: Have a scuba professional attach all components to the appropriate ports. Setup During Dive: Position the primary second stage over your right shoulder. Attach the alternate air source with a quick release in the triangle. Route the SPG hose under your left arm and secure it. Rinsing and Maintenance: Rinse with a gentle freshwater flow, ensuring the dust cap is in place or attached to a cylinder. Run water through second stages without pressing the purge button. Regulators need professional overhauls every one to two years. Caution: Do not use a regulator with issues; have a professional inspect and service it as needed.

What three special maintenance considerations do regulators have?

Rinsing Procedure: Use a gentle freshwater flow for rinsing. It ensures proper care with the first stage dust cap tightly in place or while still attached to a cylinder. Prevents water from entering the air inlet where it meets the cylinder valve. Care During Rinsing: Run water through second stages while rinsing, but do not press the purge button. It prevents water from flowing up the hose to the first stage, maintaining the integrity of the regulator components. Periodic Overhauls: Regulators require professional overhauls every year to two years. It ensures continued functionality and safety by addressing any potential issues and maintaining the regulator's reliability. Adhering to these special maintenance considerations helps preserve the longevity and effectiveness of the regulator components, contributing to a safer and more reliable diving experience.

What two special maintenance considerations do BCDs have?

Rinsing the Bladder: Rinse the inside and outside of the bladder with fresh water. Fill it about 1/3rd with water, then the rest with air. Slosh the water around, drain it through the LPI exhaust, and through each quick dump if manually activated. Repeat as needed to remove all water. Storage in Partially Inflated State: Store most BCDs partially inflated to prevent the bladder from sticking together inside.

Why does salt water cause more buoyancy than fresh water?

Salt water has dissolved minerals (salt) in it, so a given volume weighs more than fresh water and becomes more dense. Because salt water weighs more, it causes more buoyancy - more upward force. All else being the same, you have more buoyancy when diving in the ocean than when diving in fresh water.

What are the three most important considerations in choosing scuba equipment?

Suitability means that the equipment is appropriate for you and the dive. If planning a dive in cool water, your short sleeve wet suit - perfectly suitable for tropical diving - may not be suitable. Fit means the equipment is sized and adjusted for you. Many pieces of gear will not function, or function poorly, if they don't fit right. Comfort is essential, so choose gear that you can wear for an extended period without distraction.

What are the three basic parts of the PADI Open Water Diver course? What is the purpose of each part?

The PADI Open Water Diver course has three parts: Knowledge Development, Confined Water Dives and Open Water Dives.

What is the buddy system?

The buddy system is diving with another diver or divers in a team that provides shared assistance and safety benefits. - Plan your dives together. - Help each other gear up and check each other's equipment. - Remind each other of dive time and depth limits. - Assist each other if there's a problem. - Assist each other with what each wants to do on the dive.

Why should I seek an orientation, supervision and/or additional training when diving in a new dive environment?

The course provides foundational skills for local diving, but different environments may require specific techniques and gear. For instance, diving in cool environments may necessitate training in the PADI Dry Suit Diver course. When diving in new environments, seek local orientation, guided dives, or additional training based on the site's unfamiliarity. This ensures: - Optimal local diving experiences. - Comfort and avoidance of problems during dives. - Knowledge of interesting or unique features. - Proper equipment usage. - Awareness of local hazards. - Learning of any required special techniques.

What is the most important consideration in choosing a regulator? What considerations and options do I have when choosing a regulator?

The most important consideration in choosing a regulator is ease of breathing. Yoke or DIN - Yoke uses a clamp system to hold the first stage to the cylinder, while DIN involves threading the regulator into the valve. Yoke is older and more established, while DIN, with a higher pressure rating, is gaining popularity, especially in Europe and Asia. Adjustable second stage - A knob allows small air flow adjustments; this option lets you keep the regulator breathing its best over the course of its maintenance cycle.¨ Dive/Predive switch - This switch reduces freeflow (air released without control) when the second stage isn't in your mouth. Cold-water first stage - In cooler climates, the first stage can freeze, resulting in a freeflow. Special cold-water regulators reduce the likelihood of this by surrounding the first stage with a special liquid.

What is the relationship between pressure, and the volume and density of air?

The relationship between pressure and the volume and density of air is direct and proportional. As pressure increases, such as when descending deeper into water, the volume of a gas like air decreases because its molecules get compressed. Simultaneously, the density of the air increases because the molecules are packed into a smaller space. This principle is crucial for divers as it affects air spaces in the body, including ears, sinuses, lungs, mask, and dry suit if used. The changes in air volume and density with pressure impact buoyancy control, air supply duration, and adherence to safety rules during diving. For example, at 10 meters/33 feet, where the pressure is 2 bar/ata, the air volume is halved, and the density doubles. Similarly, at 20 meters/66 feet, with a pressure of 3 bar/ata, the air volume becomes one-third, and the density triples compared to the surface.

What is the relationship between my depth in water and the pressure?

The relationship between your depth in water and pressure is directly proportional. For every 10 meters (33 feet) you descend, the pressure increases by one bar or atmosphere (ata), and conversely, it decreases by one bar/ata for every 10 meters/33 feet you ascend. The pressure is a result of the combined weight of the atmosphere and water, with each 10 meters/33 feet increment adding one bar/ata to the total pressure. For instance, at sea level (0 meters/feet), the pressure is 1 bar/ata, and at 10 meters/33 feet, it becomes 2 bar/ata (one from air and one from water).

What three major body air spaces does increasing pressure affect as I descend?

The three major body air spaces affected are: Ears Sinuses Mask

If I take a volume of air from one depth to another depth, how much will the volume and density change?

The volume and density of air change proportionately with pressure variations during depth changes. As you descend, the increasing pressure compresses the gas, reducing its volume and increasing its density. Conversely, during ascent, decreasing pressure causes the gas volume to expand and its density to decrease. For instance: Descending from the surface to 10 meters/33 feet doubles the pressure, halving the air volume, and doubling its density. Descending to 20 meters/66 feet triples the pressure, reducing the air volume to one-third, and tripling its density. This relationship remains consistent regardless of the measurement system used. For example, a balloon filled with 3 liters of air at the surface would decrease to 1.5 liters at 10 meters/33 feet and 1 liter at 20 meters/66 feet. During ascent, a balloon sealed at 10 meters/33 feet would expand, risking bursting. To prevent this, venting some air during ascent allows the balloon to accommodate the decreasing pressure. The predictable relationship between pressure and air volume and density applies to any depth change, whether ascending or descending. For instance, bringing 1 liter of air from 30 meters/99 feet to the surface results in it expanding to 4 liters, with the density being 1/4th of that at 30 meters/99 feet.

What is the most important feature in my weight system?

There are several types of weight systems. Regardless of type, the most important feature is a quick release that enables you, in an emergency, to drop enough weight to float even with an uninflated BCD. This is an important safety consideration so that if you have a BCD problem, you could still make yourself float quickly.

What are positive buoyancy, negative buoyancy and neutral buoyancy?

There are three types of buoyancy: - If an object weighs less than the water it displaces, it floats. This is positive buoyancy. - If an object weighs more than the water it displaces, it sinks. This is negative buoyancy. - If an object weighs the same as the water it displaces, it neither floats nor sinks. This is neutral buoyancy.

What are the two basic fin styles?

There are two basic fin styles: adjustable strap and full-foot. Adjustable fins are open at the heel and straps hold them in place. You usually wear wet suit boots with adjustable fins, which provide warmth and foot protection when walking on shore or a boat deck. Full-foot fins enclose the heel and fit like snug shoes or slippers. You usually wear full-foot fins with bare feet or thin fin socks, so they're for warm water use. Full-foot fins have different blade sizes - some are suited to scuba, but others are best for snorkeling only.

What features should I consider when choosing a mask? How do I check the fit?

To check for proper fit, you can place most masks gently against your face and inhale slightly through your nose. They should stay in place with light suction without pushing or twisting to make a seal. Among masks that fit, these features are desirable: Low profile - A mask that sits as close to your face as possible (but still fits) gives you a wider field of view. It also requires less air for clearing of water and equalizing. Wide vision field - Beyond low profile, some masks have special shapes to accommodate more field of view. Some have side windows for peripheral vision. Silicone color - Some divers like the open "feel" of clear silicone rubber; others like the reduced glare of black. Frame color - You can usually match the rest of your kit.

How do I prepare my fins for diving?

To prepare your fins, adjust the strap on adjustable fins for a comfortable fit with your wet suit boots on. Many buckles let you put your fins on with the straps loose, then pull them snug. Full-foot fins typically require little or no preparation.

Why do I need a mask?

To see underwater because human eye cannot focus underwater.

Why is training important in scuba diving?

Training is important because: - It enables diving to be rewarding and meaningful, so you can get out of it what you want. - There are potential hazards to avoid, reduce and/or manage. - Like any adventure sport, diving has risks that you must accept.

What is trim? Why is it important?

Trim is your body's orientation and balance in the water, aiming for a horizontal position with parallel or slightly elevated feet. It is crucial for energy conservation, minimizing damage to marine life, and enhancing diving pleasure. Achieving proper trim involves the strategic use of your BCD and weight placement. Some divers opt for multiple weight systems, especially when wearing buoyant exposure suits like dry suits, to facilitate better trim without compromising emergency weight release.

Why might I use more than one weight system?

Using more than one weight system provides flexibility based on your preferences, required weight, and trim needs. Weight-integrated BCDs are popular for their simplicity and comfort. Some BCDs have nonreleasable weight pockets for trim, but divers should ensure enough releasable weight for positive buoyancy. The weight belt is a popular, versatile option, and accessory weights are used for trim adjustment. Choose the most suitable weight system with guidance from your instructor or dive center.

What are my considerations and options when choosing one or more weight systems?

Weight-integrated BCDs are common, offering simplicity, comfort, and often include trim pockets. Ensure there's enough releasable weight for positive buoyancy, even if the BCD has nonreleasable weight pockets for trim. The weight belt is a traditional option, with variations like thread-on weights or zippered pockets. It suits both low and high-weight needs, and some divers combine it with a BCD integrated-weight system. Accessory weights, used for trim adjustment, attach to ankles or cylinder valves. While they don't usually have a quick release, they make up a small portion of total weight.

What are my considerations and options when choosing an alternate air source?

When choosing an alternate air source, consider simplicity versus independence. The extra second stage and alternate inflator regulator, integrated into your regulator and/or BCD, are simple, adding minimal bulk. Some divers opt for self-contained ascent bottles or pony bottles for independent air supply. While useful, they don't replace the importance of diving with a buddy. Most recreational divers find the alternate second stage or alternate inflator regulator sufficient and popular. Those choosing self-contained ascent bottles or pony bottles usually have one of the simpler options as well. Attach your alternate air source second stage in the triangle area with a quick release, and secure the hose-mounted SPG on your lower to mid-left torso. Avoid letting anything dangle unsecured from your kit.

What features should I consider when choosing fins?

When choosing fins, focus on fit and blade size. For adjustable fins, try them with wet suit boots, and wet your feet for easy sliding with full-foot fins. Blade size is generally proportional to the foot pocket but varies among models. Larger, stiffer blades offer more thrust but require more strength. Smaller, flexible blades are less demanding but may be inefficient. Optimal scuba fins usually have a "typical" size blade. Consider optional features: Material: Influences weight and performance. Split fins: Some prefer the kicking characteristics of split-blade fins. Vents: Assist performance by allowing water passage in key areas. Quick-release straps: Facilitate easier removal. Spring straps: Auto-adjust for a proper fit and are highly durable for adjustable fins.

How do descending and ascending affect my buoyancy?

When you descend, their volume decreases, which reduces the water displaced. This reduces your buoyancy (makes you more negatively buoyant). You offset this by adding air to your BCD (if diving with a dry suit, you may add air to the suit). When you ascend, it works the other way. The gas volume in your gear re-expands and your buoyancy increases. The air you added to your BCD (or dry suit) also expands and further increases your buoyancy. To control your buoyancy as you ascend, you vent (release) the air you added on the way down.

How does breathing affect my buoyancy?

When you inhale, your chest expands, increasing your volume, displacement, and buoyancy. When you exhale, you contract your chest, decreasing your volume, displacement, and buoyancy. You'll notice that your breathing affects your buoyancy. When you inhale, your chest expands, increasing your volume, displacement and buoyancy. When you exhale, you contract your chest, decreasing your volume, displacement and buoyancy. While the change isn't large, with practice, you'll learn to use breathing to fine-tune buoyancy without holding your breath.

What do the markings on a cylinder tell me?

You are primarily interested in the serial number, working pressure and the hydrostatic test date. Local laws or regulations may require other markings. Cylinder alloy - typically a code number Serial number - record in case your cylinder is lost or stolen Working pressure - the maximum allowed fill pressure Manufacturer's identification Manufacture date Test pressure - the pressure used for periodic hydrostatic tests (more about hydrostatic tests shortly) Hydrostatic test date - there will be at least one, with additional dates for each test over time In-service cylinders feature labels, with a visual inspection decal indicating the last annual visual inspection date. Cylinders filled with enriched air nitrox may have a specific band, and Oxygen Clean/Not Oxygen Clean decals provide information about EANx filling, requiring certification as a PADI Enriched Air Diver. The PADI Enriched Air Diver course, a popular specialty, allows longer dives by reducing nitrogen through added oxygen. Enriched air, also known as nitrox or EANx, requires special knowledge and equipment, covered in the course. For more details, consult your instructor or visit padi.com.

What considerations and options do I have when choosing cylinders and valves?

You can choose from various cylinder and valve options, with popular types depending on the region. Consider material: Steel and aluminum are common materials, each with its advantages. Aluminum is resistant to corrosion and often used in tropical areas, while steel cylinders are more compact for the same air volume. Consider size and capacity, expressed in liters or cubic feet. Sizes vary, such as 8, 10, 12, and 15 liters in the metric system, and 50, 63, 71.2 (known as 72), and 80 cubic feet in the imperial system. The air-holding capacity depends on both internal volume and working pressure. A cylinder with a higher working pressure does not always hold more air than a cylinder with a lower working pressure. Choose between yoke and DIN valves. If uncertain about the regulator type you'll encounter, a DIN valve with a yoke insert is a versatile choice. Regarding valve types, reserve valves (like "J" valves) were standard before submersible pressure gauges (SPGs). Though rare now, some regions still use them. They have a spring mechanism that restricts air when about 20-40 bar/300-500 psi remains, serving as a low-air warning. However, SPGs are the primary means of managing air supply even in regions with reserve valves.

What is the purpose of Open Water Dives (step 3)?

You make Open Water Dives with your instructor at sites suited to beginning divers. You practice, apply and demonstrate what you learn in Knowledge Development and the Confined Water Dives.

What is PADI's Four E Philosophy

You need equipment, because diving is a technical activity. You need education (PADI training) to learn to dive and to progress into the underwater activities that interest you. Diving is an experience, so you need opportunities for local diving and dive travel. Without a healthy aquatic environment, the underwater world loses much of its interest and appeal.

Where do I get scuba cylinders filled? Why?

You should get your scuba cylinders filled only at reputable scuba air stations, such as PADI Dive Centers or Resorts. These stations use compressors specifically designed for breathing air, ensuring proper filtration and meeting air purity standards. Contaminants that are harmless on the surface can become toxic at depth due to pressure. Choosing trusted scuba air stations guarantees the quality and safety of the air you breathe during your dives.

What's the most efficient way to breathe dense air underwater?

Your breathing rate influences your air supply duration, with faster breathing depleting it more quickly. Pressure at depth compresses air molecules, making it denser and harder to breathe than at the surface. Deeper depths require more energy for breathing, and faster breathing, whether at the surface or any depth, significantly increases energy expenditure—approximately four times more energy is needed to breathe twice as fast. Therefore, deeper depths demand more effort and energy when breathing rapidly.

What two components make up a scuba cylinder? What does the burst disk do?

Your scuba cylinder (tank) is an aluminum or steel alloy container made specifically for storing high pressure air. It consists of two components - the cylinder itself, and the valve. The valve, made of chrome-plated brass, controls air flow to and from the cylinder. In many countries, the valve also has a burst disk. The burst disk is a safety device that relieves accidental overpressure by rupturing and releasing the air well before the cylinder would fail.

How do I prepare my snorkel for diving?

Your snorkel goes on the left side (because your regulator is on the right) of the mask strap using its clip, slot or keeper. Adjust it so that with the mouthpiece in, the tip is over the crown of your head. This puts it at the highest point when you're face down in the water. When standing up (out of water) with your mask on and snorkel in, the tip will be behind your head when positioned properly.

What two pieces of equipment do I normally use to control buoyancy?

Your weight system and your BCD (Buoyancy Control Device) Your weight system holds just enough lead weight to offset your positive buoyancy. You need this because most people float, and some of your gear - like a wet suit - also floats. Use just enough weight to allow you to descend, but you shouldn't sink rapidly. How much weight you need depends upon your gear, your physical characteristics and whether you're diving in fresh or salt water. You will learn more about weight systems and how much weight to use shortly. To actually change your buoyancy during a dive, you use your BCD. Inflating and deflating it increases and decreases your volume - how much water you displace. This adjusts your buoyancy so you can be positively, negatively or neutrally buoyant when you want. This is one of the key dive skills you'll master, and you'll begin learning to use your BCD during your first confined water dive.

A balloon fully inflated and sealed at 10 metres/33 feet, would probably _______ during ascent to the surface.

burst

As you descend in water the pressure ...

increases

The density of the air in the previous question (If you take 6 litres of air from the surface to 20 metres/66 feet, the volume will be 2 litres) would be ________ the density at the surface.

three times