Telling people you’re a rescue diver is fun. It evokes mental images of you jumping from helicopters into frigid waters like Kevin Costner in The Guardian. While becoming a rescue diver won’t make you Ashton Kutcher, it can be a challenging and rewarding experience.

I’m coming from a PADI approach, but as we’ll see, the information here applies to most of the larger organizations.

What is it?

Like most diving certifications, rescue diver has a knowledge portion combined with an applied, in-the-water component. The knowledge portion includes

• Common causes of diver stress and dive emergencies
• Identifying a diver in need
• Dive rescue procedures and injury treatment
• First aid supplies and dive rescue equipment
• Managing a dive emergency
• Rescuer health and safety
• In-water rescue skills

In addition, you’ll have to prepare an emergency assistance plan, which includes steps of emergency management for a specific dive site.

The applied part of the course is usually split into closed water (pool) exercises and open water exercises. Rescue diver is probably the most physically demanding certification, as it includes recovering unconscious divers from the water—a challenging task.

As a prerequisite, you must be CPR / First Aid certified. These are combined through a PADI certification called Emergency First Responder (EFR) that covers the same material, but you can go to any Red Cross to get the required certification. As you’ll find out when you take this course, many people like having this certification alone to increase their confidence for handling things like ordinary household emergencies.

After learning about skills in a classroom, you’ll have to perform them in the water. There are a lot of skills to do, ranging from simple things like cramp release all the way up to a complete rescue of an unconscious diver (including removal from the water). In between are things like towing a tired diver, helping panicked divers, and carrying divers out of the water.

The Recreational Scuba Training Council (RSTC), which includes organizations like PADI, SDI, SSI, and YMCA, has a complete list of minimum requirements for a rescue diver course. NAUI is one of the few large organizations no in the RSTC, but I imagine the required skillset is very similar.

How long does it take?

The length of the course varies; some shops like to really take their time when teaching rescue courses. The CPR / First AID (EFR) course can be completed in a day. Expect at least one night for covering the knowledge portion, possibly including watching videos. There is also the pool work, followed by open water exercises. Including EFR, that’s a minimum of 4 days (some of which might be evenings).

Who should take it?

Now we’re getting to the real crux of this article. Most regular divers will complete their advanced certification, if for no other reason just to be allowed to do deep dives. However, most people stop here, so why should you continue?

PADI has a corny, but accurate way of describing the progression through certifications. As a beginner diver, the focus is on taking care of yourself in the water. As you progress, your focus moves from within to becoming aware of other divers. The training follows this approach, as you begin with what is basically a review of self-rescue skills, and then learn how to recognize potential problems in other divers.

Honestly, I feel the training provided by rescue certification is not so much about actually rescuing people. Most divers are probably still not comfortable with that idea even after completing a rescue course. I think the advantages are more about increasing your own comfort level in the water. It’s not until you reach the leadership levels do you really begin to feel the possibility of using your rescue skills.

In any learning situation, there is an old adage that to teach something is to really understand it. This thinking applies here as well. To feel comfortable helping others is to really feel comfortable with yourself in the water. It is for this reason that I recommend that all those who dive regularly take a rescue diver course. You could achieve this comfort level over time with hundreds of dives, but taking a good rescue diver course will get you there much sooner.

Do you agree? Is finishing a rescue diver certification worth it for most divers?

It’s official, I finally received my PADI divemaster certification card in the mail!

Turnaround was quick, about three weeks. I also received 12 of the 15 specialty cards I was expecting. My mail lady probably hates PADI.

Next up, assistant instructor then open water scuba instructor!

Disclaimer: Do not attempt to dive with enriched air unless you have completed the appropriate speciality course. Doing so without complete training can be very dangerous.

Enriched air can mean any gas blend other than the standard 21% oxygen / 79% nitrogen that comprises what we call “air.” For our purposes in this article, enriched air will refer to a blend of oxygen and nitrogen in which the oxygen content has been raised, more commonly called “Nitrox” (or EANx, Enriched Air Nitrox). We won’t be concerned with Tri-mixes and the like—usually the domain of tech diving.

Nitrox blends increase the oxygen content of a cylinder, which simultaneously lowers the nitrogen content. This is usually accomplished by partially filling a cylinder with air (21% oxygen / 79% nitrogen), then “topping it off” with pure, 100% oxygen. Some basic math tells us the final oxygen content.

For example, imagine we fill a cylinder to 2500 PSI with air, then fill to 3000 PSI with pure oxygen. What is the final oxygen content? 500 PSI (3000 PSI – 2500 PSI) is 100% oxygen, while 21% of 2500 PSI is also pure oxygen. 2500 PSI * 0.21 = 525 PSI. Add the two together to get 500 PSI + 525 PSI = 1025 PSI oxygen. Divide by the total contents of the cylinder to get the percentage of pure oxygen, 1025 / 3000 = 0.3416 = 34.16% oxygen. That means the remaining 65.84% must be nitrogen (ignoring trace amounts of other gases in the air). We call our blend is EANx35, Enriched Air Nitrox 35 (you round up with enriched air blends).

Why enriched air?

What advantages does Nitrox provide divers? Nitrox reduces exposure to nitrogen compared to diving with air. Nitrogen is known to instigate Decompression Sickness (DCS), so less exposure is always good.

Divers take advantage of this benefit in two ways. Bottom times provided by dive tables and computers are controlled by estimates of nitrogen exposure. Less exposure means more bottom time. So the maximum bottom time on a Nitrox dive to a given depth is always higher than the maximum bottom time of an air dive to the same depth. My dive table says that an air dive to 60 ft (18 m) has a maximum bottom time of 47 minutes. The same dive on EANx32 has a maximum bottom time of 77 minutes, half an hour longer!

Not everyone wishes to dive for an hour and a half, however. The other advantage, then, is that with two identical dive profiles, one with air and one with Nitrox, the Nitrox dive will have a higher buffer of nitrogen exposure, significantly decreasing any risk of DCS. This isn’t a big deal for any one dive, but for many consecutive multi-day dives, where DCS causes are less understood, this buffer becomes important. The benefit of Nitrox also decreases required surface intervals, allowing a diver to easily fit four dives in a day.

What’s the catch?

Diving with Nitrox introduces a few more variables to track. For one, you must always check your cylinder for what percentage Nitrox it contains. The blender uses the above calculations, but any errors can affect your diving in a bad way, so for safety it is not only recommended, but required that the diver personally check their enriched air before every dive. Shops will have the appropriate equipment for doing so. I would refuse to dive with an enriched air mix I have not personally checked.

Fortunately, most dive computers come equipped for enriched air, making it straight-forward to dive with Nitrox. However, Nitrox requires modified dive tables, due to different exposures. Shops sell tables for common mixes such as EANx32 and EANx36, and your Nitrox specialty course may even come with them. The most versatile method is using something called Equivalent Air Depth (EAD).

Equivalent Air Depth calculations tell you, given a specific Nitrox blend, at what depth you would have to dive with air to get the same nitrogen exposure. With this depth, you can use normal dive tables to plan dives. Since Nitrox contains less nitrogen, this depth is always less than the actual dive depth. We can compute EAD as

EAD = (1 – O%) * (D + 10) / 0.79 – 10,

where O% is the percentage of oxygen, and D is the depth of the dive, in meters. Suppose we are planning a dive to 60 ft (18 m) with EANx34 and don’t have an appropriate table. We compute our EAD as (1 – 0.34) * (18 + 10) / 0.79 – 10 = 13.39 m, or 45 ft. We then use our ordinary dive tables, entering 45 ft (or 13.39 m) as the dive depth. This gives me a 63 minute bottom time.

Oxygen exposure

Diving with air within recreational limits, oxygen exposure never reaches critical limits—our body is always able to metabolize the available oxygen. However, with Nitrox oxygen content is increased to amounts that could be dangerous.

For instance, it is known that exposure to oxygen partial pressure beyond 1.6 can be fatal. Oxygen partial pressure is the portion of pressure due to oxygen at a given depth. Air at 1 atm has an oxygen partial pressure of 0.21 * 1 = 0.21. At 2 atm it’s 0.21 * 2 = 0.42. With this knowledge, we can calculate a maximum allowable depth on any gas blend. For air, this maximum is 1.6 / 0.21 = 7.619 atm, which corresponds to a depth of about 66 m (215 ft). In practice, it is recommended (and wise) to use 1.4 as the maximum oxygen partial pressure, to build in a safety buffer. For air then, we wouldn’t want to exceed a depth of 1.4 / 0.21 = 6.6 atm, or 56 m (185 ft). I’m guessing that won’t be a problem for most of you.

We can repeat these calculations for our Nitrox blends. Given EANx36, the maximum depth is 1.4 / 0.36 = 3.8 atm, or 28 m (93 ft), which is above the recreational limits! Keep this in mind for high oxygen content blends. What is the maximum allowable depth for EANx40 (the highest oxygen content permitted with most certifications)?¹

This is a maximum partial pressure in a single dive, but over multiple dives, your body accumulates excess oxygen that it can’t burn. Given enough time this oxygen can become toxic. Therefore, you must also track accumulation of oxygen over a running 24 hour period. You will learn how to do this and be given the appropriate tables in your Enriched Air Diver specialty course.

If these advantages sound appealing to you, I highly recommend completing your Enriched Air specialty. Most regular divers will do it at some point. Don’t let the calculations and variables deter you; they become easier over time. Again, let me reiterate that you should not dive with Nitrox unless you have completed such a course. It can be done in an evening, with no dives required (at least with PADI).

1. 82.5 ft (25 m)

I admit it. The articles I write for The Diving Blog tend to be PADI-centric. Do I think PADI is better than all the others? Not really. I did my Open Water certification with PADI and just happened to move through their system. I’m working on a PADI divemaster certification (and soon, Open Water Instructor).

To introduce a little fairness, I decided to investigate several agencies and report on the differences. The result may not be a big surprise. The differences between agencies are small. When you dig deeper you uncover the reason for this. There are international (and national) standards for certification requirements. That is, representatives from different agencies agreed upon the minimum knowledge and skills required for each certification level.

This has two implications. First, it means scuba training across the board is going to be very similar. Fluctuations in instructors are more likely to determine your individual experience. Second, it means most agencies follow the same certification hierarchy: open water diver, advanced open water diver, rescue diver, divemaster, assistant instructor / instructor. Names may very slightly, but the overall structure is the same, with each of these courses following the standards set forth by ISO 24801-2 (open water), 24801-3 (divemaster), 24802-1 (assistant instructor), and 24802-2 (instructor). The important thing here is that most standard-respecting agencies will respect comparable non-professional certifications from other standard-respecting agencies. Sometimes a peek at your log book may be required, or worst case, an accompanied dive to demonstrate your skills. Call your destination’s dive shop ahead of time if unsure.

There are a lot of certifying agencies. For my research, I looked into those that are a) international, and b) the largest. Here some information about each of those:

Professional Association of Diving Instructors (PADI)

PADI is by far, the largest certifying agency in the world, with over 5700 dive shops and resorts in over countries. It was founded in 1966, by effectively splitting off from NAUI out of frustration.

PADI revolutionized scuba instructor by turning it into an hobby for everyone, rather than elite swimmers and athletes. The learning material reflects this, by breaking down every process into distinct pieces for easy consumption. This approach to learning extends all the way up the ladder to divemaster and instructor levels. Instructors are expected to adhere to every aspect of the PADI system, not only what is taught, but how it is taught. This makes the PADI system incredibly consistent across the globe.

Being the largest certifying agency (issuing two-thirds of all certification cards in the US each year) comes with its criticisms. First, is how PADI constantly attempts to upsell its customers. The entire last chapter of the Open Water manual is an advertisement for Advanced Open Water. Almost the entire divemaster manual says why you should immediately go on to the PADI instructor-level. PADI is a for-profit corporation, and this sometimes reflects in their material, with many jokingly referring to PADI as, Put Another Dollar In.

The second criticism, however, has less of a basis. Many claim that PADI “dumbs down” scuba diving for mass consumption. It is true that they break the learning process down into its simplest components, but this can hardly be considered a bad thing. This elitist attitude neglects the advantages that have come from the boom in scuba diving, namely easy access to dive sites and equipment practically anywhere in the world.

National Association of Underwater Instructors (NAUI)

NAUI is the oldest certifying agency in the world, established in 1959. NAUI even boasted Jacques Cousteau as a member of its advisory board at one point. Another distinction belonging to NAUI is that it is also one of the few non-profit agencies (the only big one, as far as I can tell). NAUI’s reputation has earned it a spot as the certifying agency for many colleges and universities, the US Navy, and even NASA.

While not a member of Recreational Scuba Training Council (RSTC), NAUI is ISO certified.

Scuba Schools International (SSI)

SSI was founded in 1970, and has over 2400 offices in 110 countries. SSI takes a unique approach, in that training is only provided through one of their worldwide centers. Despite this centralized approach, SSI gives its instructors more freedom in how material is presented, giving instructors the opportunity to adjust style based on student participation. I suspect their centrist policy allows this freedom, since instructors are teaching within a dive center where styles and student reactions are easier to monitor.

SSI emphasizes its teaching style of “comfort through repetition.” I don’t see how this is much different than most agencies, but the most noticeable result is that SSI requires five open water dives for basis certification, rather than the four required by the standard (and followed by most agencies).

Scuba Diving International (SDI)

SDI is the recreational arm of Technical Diving International, the largest tech diving training organization. It is also the baby of the group, recently founded in 1999. Despite getting a late start, SDI now has over 2200 authorized dealers worldwide, putting it just a hair behind SSI in size (although I don’t know the geographic distribution of either).

While a standards-recognizing agency, SDI is unique in two ways. The first is immediately noticeable in their Open Water course: all students are required to have modern dive computers. SDI gets students used to diving with computers from the start. This could be seen as an advantage, since it eliminates the need to teach dive tables and introduce further confusion. I have also heard this as a criticism, since should a computer fail, the user is left with no alternative means of dive planning.

Secondly, SDI is the only agency that offers a certification for diving alone, Solo Diver. Every other agency mandates diving with a buddy at all times. I imagine this aspect of SDI was influenced by its origins as an offshoot of TDI, where diving alone is normal.

If one of these stands out to you, or you find their teaching philosophy appealing, then go with it. Otherwise, don’t fret about any particular agency. Instead, spend your time finding high-quality instructors, either through recommendations or online reviews.

Is there any other reason you would suggest one agency over another? What is your experience diving abroad with the smaller organizations?

Following basic certification, many divers immediately move on to an advanced certification level. Especially since some activities (like deep dives) require an advanced card.

Advanced certification has been criticized for being somewhat of a misnomer. In all certification agencies, the advanced level is attained with a relatively small number of dives. For this reason, it has been suggested to rename the advanced open water level to something like, “Open Water II” (as it was previously called by NAUI) or “Comprehensive Open Water”, to better indicate the nature of the course. Regardless of what it is called, those that dive regularly will want to complete the course at some point.

Advanced certification is built around specialities. The idea is that exposure to many different varieties of diving increases your experience level and encourages further development. How much exposure is required differs between agencies. I’ll cover the four largest.

PADI

PADI requires five “adventure” (i.e., specialty) dives to qualify for Advanced Open Water (AOW) certification. One of these dives must be an Underwater Navigation specialty and another the Deep Diving specialty. The other three are the diver’s choice. (Note: Until 2006, night diving was required.)

Unlike other organizations, PADI does not require a minimum number of dives for certification. This means that a diver could be Advanced certified with only 9 dives (4 open water dives + 5 adventure dives), all of which are instructor certified. This makes PADI’s AOW certification the quickest, and the easiest to criticize.

NAUI

NAUI calls their second certification level, “Advanced Scuba Diver”, with requirements similar to PADI’s. However, NAUI requires six open water dives to qualify for certification. One must be navigation, another must be deep diving, and a third is required to be night or low visibility diving. The other three are chosen at the diver’s discretion.

Also like PADI, there is no minimum number of dives required. With only one additional dive required, NAUI Advanced certification is almost as quick as PADI.

SDI

SDI prides itself on its Advanced Diver Development Program having higher requirements and demanding more experience before certification. As opposed to just a certain number of speciality dives, SDI requires candidates to complete four specialty courses, with no requirements on the type of specialties. Each specialty requires about two dives, so eight dives total.

Another distinction is that SDI requires a minimum of 25 logged dives to complete certification. Once reached, the scuba diver brings in their dive log and four specialty cards to be awarded Advanced Scuba Diver certification.

SSI

SSI’s Advanced Open Water Diver certification is more similar to SDI than any other agency. They also require completion of four specialties, with no requirements on the specialty subjects.

24 logged dives are required to complete certification.

This should give you an idea of what’s required to complete Advanced certification. The student must decide what specialties they want to explore. In my opinion, the most valuable non-required dive is a buoyancy related specialty. Proper weighting and buoyancy control throughout a dive are valuable skills to master early. Other than that, it should be straight-forward to follow your interests in deciding.

What specialities would you recommend? What do you think about the whole “Advanced Diver” misnomer?