What should I learn in Open Water?
Most divers begin their education with an Open Water Diver Course from PADI or another scuba training agency. Since they are brand new to the sport it can be hard to know what you should be getting out of the course. Here is an incomplete list of some things that you should be able to do by the end of every Open Water Course. If you did not learn how to do these things in your course talk to your instructor or go out and seek additional training/practice.
Breathing
How to breathe continuously when underwater (never hold your breath while ascending) - so you don't get hurt.
Breathe from a regulator (a mouthpiece that delivers air via a hose attached to your air tank) underwater even if it freeflows (air comes out and won't stop).
How to find your regulator, put it back in your mouth and start breathing again if it comes out or is pulled out.
How to track how much air you have left (you use a pressure gauge that measures the pressure in your tank) so you don't run out - you should alway be aware of approximately how much air you have remaining.
How to share air via a 2nd regulator from your buddy's tank if you run out of air.
How to breathe from a snorkel at the surface and clear it if water gets in it
Mask use
How to put on a mask so you can see underwater
How to clear water out of your your mask if some leaks in
How to put your mask back on if it gets knocked off or your choose to take it off
How to breathe, swim, and stay calm underwater even if you lose your mask
Weighting
How to quickly release enough weight from your gear so you can easily float at the surface in an emergency.
How to determine the amount of weight you need to be able to sink - so you can descend underwater. Never dive with more weight than you need to sink. Diving overweighted increases your risk of not being able to reach the surface, it also increases your air consumption and makes your buoyancy harder to control.
How to perform a weight check in the water to determine if you have too much or too little weight. With a nearly empty tank and empty BCD you should be able to float at eye level with a normal full breath, sink if you exhale, and rise back up to the surface if you breathe in again. If you can't sink you need a bit more weight. If you can't return to the surface without adding air to your BC you are overweighted. If performing the check with a full tank at the beginning of the dive add an appropriate amount of weight after the check to account for the mass (weight) of air you'll lose during the dive (often about 4 lbs, but it can be a bit more or less depending on the capacity of your tank).
How your weight should be distributed (how much in a belt/harness or in BCD pockets vs trim weight pouches) on your equipment and configured so that an appropriate amount can be quickly released to enable you to easily float with your head above water at the surface in an emergency.
Ensure your BCD has enough lift capacity to float on its own if you take it off. This applies in particular to our cold water diving where we wear a lot of weight (compared to warm water divers) to allow us to sink in our thick floaty wetsuits or drysuits. Ensure that your BC has sufficient lift capacity to compensate for loss of buoyancy in the event of drsuit flooding (if applicable). It may be appropriate to split weight between 2 or more systems - such as BCD pockets and a weight belt or harness if you are using a lot of weight in a cold environment.
Don't be content with your instructor just giving you weight or telling you how much you need. You should know how much weight you are using, and you should perform a weight check to determine the right amount for every dive.
Buoyancy skills
How to use your BCD and (if applicable) drysuit to maintain roughly neutral buoyancy by adding or venting air from your BCD/drysuit as you change depths and the air compresses (as you go down) or expands (as you go up)
How to use your breathing (breath slightly deeper or shallower) to fine tune your buoyancy and be able to hover effortlessly
How to stay in one place in the water column - you should be able to go up or down at will and strive to never hit the bottom or shoot toward the surface by accident. If you haven't mastered this then first make sure your weighting is correct (buoyancy is harder if under or overweighted) and practice until you can control your position. Good buoyancy is critical for your safety.
How to ascend and descend at a slow, controlled rate of less than 30 feet per minute by adding or removing air from your BCD and (if applicable) drysuit as needed. If you cannot stop your ascent or descent at any time you need additional practice. You should be able to descend without hitting the bottom and ascend without corking up to the surface.
Trim
Your "trim" is your attitude/angle in the water relative to a theoretical flat bottom. Your body should be roughly horizontal most of the time when you are diving - we call this being "in trim".
Horizontal trim is important for efficient propulsion and gas (air) consumption. It helps you achieve and maintain neutral bouyancy and control your position in the water column.
How to adjust your gear and posture to achieve good trim - which may include trying different combinations of weighting systems (BCD weight pockets, trim pouches, weight belts, weight harnesses), tanks (e.g. steel vs aluminum). Carrying a bit of tension in your core and leg muscles to maintain proper posture underwater and playing with the position of your arms (often reaching slightly ahead and spread out like a skydiver) also helps.
How to move weight toward your head (e.g. taking a few pounds off a weight belt and moving to trim pockets that are higher on your torso) can correct trim that is "head up". Moving weight toward your feet can correct trim that is "feet up". This can be done by adjusting the position of both your weights and your tank.
Propulsion / Finning
Propulsion or finning refers to how you move yourself around in the water. For most of us (with functional legs and feet) that is going to be by using your fins. As divers we strive to avoid using our hands (sculling) for propulsion.
A great instructor will introduce you to different finning techniques like flutter kick (most common for beginners), frog kick (less effort and more stable than flutter kick), helicopter turns (to change directions), and back finning (to go backwards).
Buddy awareness, contact, and communication
Know where your buddy is at all times - this means you need to stay with them - which requires that you have good control of your buoyancy (up and down axis in the water) and solid propulsion (which allows you to move within the horizontal plane in the water).
Keep your buddy within a few feet from the time you enter the water until the time you exit so you can reach each other within a couple seconds if needed to assist with a problem including sharing air.
Know and practice hand signals with your buddy so you can communicate underwate.
Dive planning and safety
How to plan a dive on your own with a buddy (you should be doing this on your own in your course during your final dive) taking into account the following limits:
turn pressure - turn around based on using some amount of your air
ascent pressure - when should you be ending your dive so as to not run out of air
depth limit - what is appropriate for your training, experience and the dive site?
decompression and time limit - if you stay down too long, you can absorb a lot of nitrogen in your body tissues which can bubble out on ascent causing injury or death, you avoid this by diving conservatively well within the no decompression limits of your computer or dive table
plan for a safety stop at 15 feet for 3 minutes or more on every dive
How to consider local environmental conditions in your dive plan
Consider conditions - weather, waves, tides, currents, boat traffic or other hazards
Have an emergency plan - how can you get help if something goes wrong
Safety equipment - is emergency oxygen available? a first aid kit?
At what point should you cancel or reschedule the dive if conditions are not favorable?
How can you know what to expect at your dive site - get an orientation from an experienced local diver or professional
Make and agree to a plan for what to do in the event of buddy separation
How to use a written (don't count on your memory) pre-dive buddy safety checklist to make sure:
all your equipment is working (e.g. air turned on, everything connected, no missing equipment)
all your buddy's equipment is working
you and your buddy are familiar with each other's equipment so you can help each other if needed (e.g. how to share air underwater and remove weights at the surface to help each other float in the event of an emergency)
How to use surface signalling devices
Always carry signalling devices that allow you to be easily seen and heard at the surface in local conditions. This can help re-unite you with your boat or buddy, warn approaching boats not to run you over, or signal for help in the event of an emergency.
Examples of signalling equipment includes a whistle, surface marker buoys (SMB) and delayed surface marker buoys (DSMB). In some (especially remote or high current) areas GPS enabled signalling beacons may also be appropriate.
Dive Equipment
How to assemble your own gear including attaching your BCD and regulators to your tank.
How to properly maintain your equipment to prevent safety issues - and recognize when tanks or other gear needs to be serviced/maintained.
How to put on, remove, and choose appropriate gear (mask, fins, snorkel, wetsuit/drysuit, hood, gloves, etc.) for your diving conditions
How to use your dive computer for dive planning and dive monitoring to stay within depth, no decompression, and ascent rate limits. You should always be aware of your depth, and remaining no decompression time - do not rely solely on your instructor. You are here to learn how to do this yourself.
Exercise good judgment and build safe habits
Learn when it may be appropriate to not dive or end a dive - any diver should feel comfortable ending any dive at any time for any reason without being pressured by their buddy to continue.
Learn how to dive conservatively well within the limits of your training, air supply, and no decompression time.
In an emergency you will be most likely to do what you have practiced - so practice habits that keep you safe like keeping your regulator in (or at least avaible to put in quickly) and mask on until you have exited the water.
Always plan on and make a safety stop when the depth of your dive calls for it.
Practice emergency skills with your buddy on a regular basis even after your training class is over - having regularly practiced skills like removing your mask and continuing breathing and sharing air with a buddy will mean that you are ready to handle problems should they occur in a real life situation.
Don't dive if you're not feeling well - especially if you have a cold or other respiratory illness that could make it difficult for your ears, sinuses, and lungs to equalize - it's not worth it. You could get hurt.
After a dive - log your dive as an opportunity for learning and reflection and debrief with your buddy.
What went well?
What problems did you have (if any)?
How could you do better next time (if applicable)?
Create a culture where every dive is an opportunity for learning. Open communication of concerns, problems, and successes builds a safety-oriented culture.
If you dive with professionals, choose professionals who follow best safety practices.
Don't dive with buddies who disregard safety rules or who don't follow the buddy system.
Continue diving and seek additional experience and training to build and reinforce your dive skills and judgment.
Understand the science of diving
Know how pressure affects gas/air as your underwater depth changes
Know how breathing pressurized gas at depth can affect your body and how to limit the risks of pressure and decompression injuries that can result from breathing air at depth