Primary rule: when on a dive boat, listen to and follow the Divemasters’ and crews’ instructions and advice.  They are there in part for your safety and to assist you. 

Use your head and not the boat’s.  If you get seasick (see Question 62), then upchuck over the railing, down wind from everyone.  In SCUBA circles, reverse peristalsis is also termed feeding the fish.  Note that there are no fish in the boat’s head to feed.  Making a smelly, slimy mess in the lavatory is unnecessary and very bad form.  Just because it is called a head does not mean that is where yours goes. 

Do not put your weights on anything higher than what you want them to slide off of, and on to your toes.  Or worse, your neighbor’s toes!  Particularly when your neighbor is twice your size.  Not only can those weights break a toe but more importantly they could ruin the dive.  If possible, keep those weights on the boat deck under your bench or otherwise out of the way and secure.  Additionally, be sure to secure tank(s) as instructed by the crew or Divemaster.  A loose cylinder on a pitching boat can be deadly; to everyone, including you. 

One thing that many do not want to endure is listening to that braggart who has dove everywhere, knows it all, and damn well wants everyone to know it by loudly expounding on how wonderful they are.  Dive stories and helping other divers are one thing, but just remember you are not the only one who paid good money to get on that dive boat.  Be considerate, it makes for a better time for everyone. 

On many dive boats, there is a table, bench, or other spot reserved for cameras.  Do not leave open drinks in those areas.  Spilling a sticky drink on a camera or having to work on your camera in an area where some stroke has spilled a drink is aggravating, if not expensive.  Be considerate. 

Another common blunder is for some newbie to spit or put defogger in their mask and then dip the mask in the camera rinse tank.  Think about it.  Underwater cameras can easily cost thousands of dollars and repairing them is expensive, not to mention maybe missing that shot for which someone (you?) paid good money to dive for.  If you do not know which tank is for mask rinsing and which is for cameras, then ASK.  If in doubt, do not dunk that mask.  There’s a whole ocean (see Question 15) just over the side of the boat! 

While we are talking about photography.  If you are into taking photographs, remember that once a photographer has chosen a photo opportunity, it is theirs until they voluntarily abandon it.  Do not invade another’s photographers photo set-up!  

On a dive boat there are usually areas which are designated as dry.  That does not mean you cannot drink there.  It means do not invade that area when wet.  Please dry off before entering those areas. 

Tipping is a controversial subject among some divers, but Divemasters and the boat’s crew are generally not independently wealthy.  In my opinion, it is very good form to leave a gratuity, particularly if they have made your dive(s) go smoother and/or more interesting.  What goes around, comes around.  

If at all possible, it is generally accepted etiquette to return recovered dive gear to its owner.  Over the course of your diving, you too will lose gear and will appreciate its return. 

Touch as little as reasonably possible when diving.  Humans are tactile animals, but putting that pinky on a blue ringed octopus could be the last less-than-brilliant thing you do.  Touching aquatic creatures can also wipe away their protective coating of slime and leave them open to disease. 

Buoyancy control is like gun control, except instead of placement of the bullet on a target, it is the positioning of your body in a water column.  Learn how to keep yourself and your equipment from touching marine organisms and ecologically sensitive terrain. 

Do not chase, harass, or kill our underwater buds unless it is legal to do so and you are going to use/eat the beast.  Lobster (bugs) and shellfish in season taste great, and are themselves a good reason to dive, but use common sense and maintain your fishery.  Shooting that huge Jew fish at a wreck may be legal in some places, but it might also be the reason some of your compatriots dive there.  It is NOT sporting to take a fish that comes up to you to have their belly scratched!  If you take game, PLEASE take it away from structures used for underwater sightseeing.  Thank you! 

Shore divers particularly take note.  Do not change into your birthday suit where you can be seen.  Even though you have a great looking, tanned body, there are shoreline residents who would rather not see it.  Beachfront residents often have political clout (money).  Keep your dive site open.  Be considerate of the local inhabitants.  That includes loud noises, particularly early in the morning, e.g., banging tanks, opening tank valves, yelling, honking, etc.  And, for heavens sake, pick up after yourselves and do not mictrate (see Question 36) in the petunias!  That really did not have to be said, did it? 

   
If you want to dive, then you must be reasonably healthy and get the professional training that will lead to your becoming an open water certified SCUBA diver (see Question 79).  To SCUBA dive without professional training is exceedingly risky.  You need better survival odds! 

Telling you why you should become a certified SCUBA diver is difficult.  We each have our own reasons for doing what we do, but for me it has changed the way I think about life.  Some of the reasons I enjoy being SCUBA certified are listed in Listing C. 

Listing C.  Reasons I Enjoy Diving.  

The feeling freedom,

the self-discipline, self-sufficiency, and self-esteem SCUBA certification engenders,

the opportunities for exploration and travel and to meet a lot of great people,

diving a paradoxically benign, yet potentially hostile, environment,

expanding my capabilities, knowledge, and life experiences,

learning more about myself, and

the opportunity to understand more fully the inter-relatedness of life on this planet.  Being able to explore relatively unfettered, a totally new ecosystem is like going to another planet {yet being able to go back home and sleep in your warm bed}.

When other divers are asked why they dive, they respond: 

I dive because I love life.

I dive so that I can be free and be with the greatest concentration of life on this planet.

Once you go beneath the surface, you will never look at the water the same way. Going to the ocean and not diving is like going to the circus and standing outside of the tent.  It’s the “Greatest Show on Earth” but you have to pay the admission price to get in.

SCUBA divers do not have the limitations that are imposed on snorkelers.

I love fishing and SCUBA is a great way to check out the fish.

I love diving on wrecks, especially when you know the history behind them.  Being able to stand on the bridge and travel back in time on a ship that sailed 300 years ago is awesome.

SCUBA is probably as close as I will get to the feeling of weightlessness in space.  It is so cool to be suspended along a wall and look down into the dark, seemingly endless, void (see Question 51).

Guess I am just an old adrenaline junkie.

SCUBA diving is always different.  It is a change of pace.

SCUBA diving gives me the opportunity to try my hand at photography and videography.

Diving is like traveling to another planet and marveling at the alien life forms so strange that you won't even recognize the animals as being animals.

I am in awe of the beauty and mystery.

The main reason I dive is to be underwater breathing air.  The rest is just icing on the cake.

Diving does not need a purpose.  It is the objective and needs no justification.

Your reasons for becoming certified and diving may differ or parallel those of ours, but one thing is certain: giving SCUBA a try will expand your horizons!  
  

 
You are about as likely to run out of air while diving as you are to run out of gas in your auto while driving.  If you pay attention to your pressure gauge and the length of time of your dive and surface with a margin of safety, then the probability of running out of air is rather remote.  Additionally, the total failure of your breathing equipment, if properly maintained, is highly unlikely (see the ‘You Are Well Suited for SCUBA’ section for equipment info). 

In 1997, DAN (Divers Alert Network) reports eight diver fatalities directly attributable to running out of air.[C]  Even so, it appears to me that running low or out-of-air puts the diver at much greater risk of panic, thus possibly contributing to other fatalities.  Most certifying agencies recommend that a diver be back on board the dive boat with 300-500 psi of air left in the tank.  If you have to hold underwater for a passing boat, swim against a current, share air with your buddy, swim ashore in rough surf, or deal with an entanglement, then you will likely need more than just your usual amount of air to make it back.  Give yourself air to spare! 

During pool sessions, you will practice several scenarios of sharing air.  In most of them the, low-on-air buddy calmly approaches you, calmly gives the "share air" signal, and calmly takes your proffered second stage.  In real life, what usually happens is your buddy (or someone else) will frantically swim to you, grab the second stage from your mouth, and possibly cause you to lose balance.  That is why to be truly prepared to share air, you must be ready to find and use your own alternate air source and be ready to take control of a diver who may be experiencing panic.  You cannot share air for long if that diver is a hoover (consumes mass quantities of air) and you both run out of air.  Always maintain a margin of safety. 

Divers who try to extend their bottom time by sucking that last draught of air put themselves and others at significant risk.  Divers who do not monitor their gauges risk potential tragedy.  It is not worth it.  If you just have to dive longer (not exceeding the dive tables of course), then get a bigger tank or use your air more efficiently. 

The regulator (the second stage regulator is what you breathe from - see Question 90) is simple, sturdy, and usually designed (see Question 97) so that if it does fail, it delivers more air (free flows), not less.  During your open water class, you will be taught how to breathe from a free flowing regulator, a procedure you should practice periodically.  Besides the reliability of your regulator, you have an extra second stage regulator (your octopus or safe second - see Question 90) and your buddy’s octopus.  In addition, many divers carry a completely redundant air system with its own regulators (see Question 99).  The chance of all them failing is miniscule.  

Low-on-air or out-of-air (OOA) emergencies occur primarily because the diver does not monitor their air.  Yet, even running low on air with an unbalanced regulator (see Question 97) is not real easy because when the pressure in the tank gets lower you have to suck harder and harder on the regulator to obtain the air.  Additionally, there are audible devices (including dive computers) that can be set to signal you when you are running low on air.  Regardless, do not depend solely on an (in)audible alarm or a harder breathing regulator to warn you of low air.  Monitor your and your buddy’s gauges. 

Even if all of a sudden you run out of air and you are no deeper than 60 feet you almost certainly have enough air to reach the surface safely (remember to keep letting air out of your lungs as you ascend).  As you ascend, water pressure on your body decreases allowing the air in your lungs to expand (see Question 49).  Additionally, it is likely that you will have another breath or two you can take from your regulator as you ascend.  So stay above 60 feet and out of caves and wrecks until you are comfortable at depth and there is no reason to fear (nor should you) running out of air underwater.  You can further minimize OOA problems if you get your equipment serviced regularly, always dive with a buddy, watch yours and your buddy’s gauges, and stay above 60 feet. 

Then there is the condition of over-breathing your regulator.  Over-breathing your regulator occurs when a diver over-exerts themselves while under-ventilating (breaths are not frequent or large enough and you feel like you cannot catch your breath).  This overexertion (caused by exercise or panic), with the feeling of suffocation, hits suddenly and generally without warning.  You should never experience a shortness of breath while diving underwater.  At the first signs of overexertion you should cease all activity, breathe deeply, and recover fully before continuing.  Loosening your exposure suit and BC (buoyancy compensator) in the chest area can be helpful.  If at the surface, on shore, or aboard the dive boat, then removing the weight belt is also helpful (do not remove at depth to avoid dropping the belt!). 

I experienced ‘over-breathing’ my regulator while training for the Rescue Diver Certification because of too enthusiastically swimming against a current.  Fortunately, I was on the surface and near the boat’s dive platform.  To resolve the problem I loosened my exposure suit and rested.  My brother experienced the same sensation when fighting surf during a shore dive in restrictive dive equipment and a weight belt that was tightly cinched.  He eventually had to return to shore to ‘catch his breath’ by removing the belt and loosening and removing equipment.  It is not a pleasant sensation.  Do not let it happen to you.  Do not exert yourself beyond your capacity to obtain air from your regulator. 

Some people worry about the potential of their high-pressure hose (connects the first stage regulator to the pressure gauge - see Question 90) rupturing and thus losing all of their air.  In reality, the high pressure orifice is very small (about .005 inches) so, if the high pressure hose does rupture, the amount of air escaping should not be catastrophic for the open water diver.  If it does happen, the diver should notify their buddy and begin a normal ascent immediately (see Question 98).  You should have no problem reaching the surface with a controlled ascent unless in very deep water and low on air to begin with.  Yet, even then you still have your buddy and/or redundant air source, don’t you? 

When you decide to get SCUBA certified you may ask yourself, “Who is going to certify me?”  The answer to that question depends on with which agency your instructor is affiliated.  Your instructor trains you and vouches for your satisfactory completion of the open water SCUBA certification requirements (see Question 80).  However, you are actually issued your C (certification) card by the authority of the instructor’s agency.  Though it is relatively rare, an instructor may be certified to and does instruct through more than one agency.  You will also notice that your local dive shop, through which an instructor usually works, is typically affiliated with one or more of the agencies. 

There is a plethora of open water SCUBA certifying agencies worldwide.  At last, count there were at least twelve based in the U.S. alone.  A partial, alphabetical listing of those in the U.S. include: IANTD, IDEA, MDEA, NASDS, NASE, NAUI, PADI, PDIC, SDI, SSI, WASI, and YMCA (see Figure D).  Note that in 1999, SSI and NASDS merged and could eventually form one organization.  Additional certifying agencies that offer advanced, specialized, or foreign (to U.S.) SCUBA training would include (list provided in part by Dr. Larry “Harris” Taylor): 

Figure D.  Requirements* for Open Water Certification by Agency. 
(*Mnimum standards when data was compiled and subject to change.) 

  OK then, which certifying agency is the best?  

One good way to start a fight is go into an X affiliated dive shop and defiantly proclaim, “X certified divers are well-trained if they know in which orifice to insert their snorkel, let alone what a snorkel is.  Z agency trains much better divers.”  Try that on the Internet at the rec.scuba newsgroup and you will be flamed (severely chastised) as a troll (someone just asking to start something). 

My open water certification was issued by PADI.  Why?  Because, at the time I began my training, I did not know the difference between PADI and a rice field.  It just happened that the dive shop nearest to my apartment was affiliated with PADI and they offered an ‘Executive Course’ (a 1:1 student-to-instructor ratio geared to meet based on my time constraints (see Question 68)). 

It is my opinion that for your open water SCUBA certification, the specific certifying agency is not critical {and now I will get flack from all the agencies}.  All the certifying agencies in the U.S. exceed the minimum standards for entry level SCUBA instruction.  The minimum certification standards were originally written by the Recreational Scuba Diving Council (RSTC).  RSTC was composed of representatives from IDEA, NASDS, PADI, PDIC, SSI, and the YMCA.  Those ANSI (American National Standards Institute) X-86.3 and Z-375.1 standards specify the minimum course work, student age, water skills, health requirements, and the completion of at least four open water dives for certification. 

Now, it is true that some of the agencies require a bit more work or an extra open water dive for certification.  Yet I have not seen any objective literature documenting that being certified by one agency over another puts the student at less risk.  Additionally, they all monitor (to various degrees) their instructor’s teaching and have formal grievance procedures if problems arise.  Further, it is my opinion that the wise diver will not stop training with just the basic open water certification.  The additional training you hopefully avail yourself (see Questions 11 and 12) and your own diving experiences would soon level the field as to one agency being slightly ‘better’ than another. 

It has been said that a larger percentage of divers that become injured are PADI divers.  It has therefore been argued by some that PADI divers are not as well trained as divers trained by other agencies.  It may be true that more PADI divers are injured, but it is also true that PADI issues the majority of the C-cards in the U.S. There simply are more PADI divers to be injured.  According to University of Rhode Island National Underwater Accident Data Center figures, from 1974 to 1987 the fatalities per 100,000 divers went down from 12 to 4.5, but PADI’s market share went up from 25 percent to 65 percent.[Y]  Those figures support the contention that PADI trains as safe an open water diver as any of the other agencies.  It really boils down to how well the instructor presents the material and the ability and desire of the student to absorb it, not the agency.  

All of the certification agencies mentioned above and in Figure D enable you the same privileges or rights to rent and buy SCUBA equipment, get air refills, and to go basic open water diving.  A SSI affiliated dive shop is just as happy to sell you a tank or BC as is a PADI shop if you are certified via NAUI or the YMCA. 

That said, there may be several other factors you may want to consider in your selection of a certifying agency, but for most, they will not be a factor.  It may be a bit more of a hassle getting advanced certification through an agency other than the one you started with.  Yet all the agencies are eager for you to get that advanced training (thus generating more income for the agency).  Note though that some of the agencies may want you to demonstrate certain pre-requisite skills if you were not previously trained through them.  Additionally, if you ever plan on becoming a Divemaster, Assistant Instructor, or Instructor, that is turn Pro, then you may want to start your certification process with the agency most likely to employ you on that tropical island where you will be relocating. 

Finally, you will want to be sure that your C-card will be recognized at that far, far away dive resort.  If you get certified through one of the above agencies, then you can be almost positive your card will be accepted.  If you have any doubts then contact that dive resort directly, work through your travel agent who will contact the resort, or get certified by all the above agencies.  In other words, cover your bases and then do not worry about it, just be sure to bring along your dive log as insurance (see Question 111).