I've been diving for a while. In 1976, I received my first C-card after taking a three week PADI class, which is an anachronism these days. Three day classes are now their norm. In 1978, I became one of their instructors. In 1984, I crossed over to NAUI. In 1990, I ran my first instructor course. In 1995, I picked up IANTD instructor certification. I have thousands of dives in places all over the Pacific. I've dove pristine reefs in the Philippines and the Solomon Islands, kelp forests in California, wrecks in Truk and the Solomon’s, and ancient, man-made underwater structures in Yonaguni, Japan. After 26 years, I thought of myself as both very experienced and highly competent. Then the boss purchased three RB-80 rebreather units.

Rebreathers have two major advantages over open circuit scuba equipment; a diver uses much less breathing gas and produces few or no bubbles. An open circuit diver with a respectable breathing rate using a single tank may be able to stay underwater for an hour depending on depth. A diver with a rebreather can remain there six to eight times longer or more with the same amount of gas. This becomes a real advantage when the breathing mixture includes expensive helium. A diver with a rebreather also doesn't spew a cascade of exhaust bubbles every time he or she exhales. Marine life isn't frightened and you can approach much closer to photograph or video the critters. And in the unlikely event you plan to place a C4 charge on your opponent's pier or vessel, sentries won't be able to track your bubbles as you swim in to accomplish your nefarious task. This was something the FBI was concerned about in the aftermath of 9/11 when they contacted numerous dive shops and training agencies for lists of their rebreather divers.

Rebreathers have some serious drawbacks as well. They can be damn dangerous. The casualty rate for rebreather divers is many times higher than for those using open circuit. Malfunctions can cause hypoxia, hypercapnia, and CNS oxygen toxicity. A flooded breathing loop may produce a "caustic cocktail," where the diver sucks in an alkaline solution, which can cause extensive burns to the mouth, throat, and lungs. Rebreathers are also expensive. The cheapest units retail for more than two thousand dollars.

Rebreathers are sufficiently different from open circuit and each other that comprehensive training in the operation of the specific unit the diver intends to use is needed before he or she is allowed to venture out unsupervised. Buoyancy is no longer controlled by breathing. Breathing gas is either in the diver's lungs or in the rebreather's counterlung. Controls and proceedures are unique. For many of us, this goes against years of ingrained methods of performing. Required preparation, as well as general care and maintenance is much more intensive. Constantly monitoring one’s physical state is absolutely essential.

Ethical rebreather manufacturers and suppliers require sufficient training in the unit before you can take it home. The amount of training varies depending on the unit, who's doing it, and what the manufacturer requires. As is common in this industry, sometimes the curriculum is shortened to accommodate the expedient interests of the instructor. However, the RB80 is produced by Halcyon and their only authorized training organization is Global Underwater Explorers (GUE). GUE has a reputation for not cutting corners and for providing the most challenging training in recreational diving. Andrew Georgitsis, their Director of Training agreed to instruct the class.

Andrew showed up late. The boss and I were bored as we waited at Naha airport on a Sunday night with nothing to do but watch a World Cup soccer match on the airport’s communal TV. To be honest, it wasn't Andrew’s fault. His flight from Tokyo had been delayed for some reason that was never explained. Actually, I was surprised that he was still vertical. He got on a plane to fly to Okinawa after a layover of only eight hours in Seattle, his home. He had just returned from his last class in Croatia. I would have been walking into the walls. He was merely grumpy.

We started the next evening in a classroom at the Torii Education Center. Andrew introduced himself, explained the mission of GUE, and contrasted the DIR (Doing It Right) philosophy with what is common practice in diving these days. We were then shown video clips on how various skills were to be executed to his satisfaction during the next two days of DIR Fundamentals training.

The Fundamentals class was required because Andrew wanted us conversant with DIR, which is a holistic system of diving that originated in the Florida cave community. Procedures for the RB80 incorporate DIR. Depending on whom you listen to, DIR is either the holy grail of diving, or a sinister doctrine designed to create frog-kicking automatons. Actually, it's a well-thought out system that stresses simplicity, physical fitness, good skills, teamwork, and proper mindset. It's rigid in its application, but it does make a lot of sense, something that other ways of diving often don't.

The next morning, we found ourselves outside the scuba locker where we configured our gear. For the first time, we heard the infamous, "What the hell is that, Chief?" Andrew is very direct with his comments. Another one of my personal favorites was, "You don't think I flew 3000 miles just to stroke you, do you?" Actually, it was refreshing to hear someone who wasn't politically correct and touchie-feelie.

In the afternoon, at the Sunabe Seawall, we were face down on the hot concrete practicing fin kicks. I already was adept at the frog kick, but we were also expected to do the modified frog, modified flutter, backward kick, and helicopter turn. God never intended man to do the last two, so they violate the laws of nature. That didn't seem to matter to Andrew.

In the water, Andrew set up a course with a cave line, which we were to follow while practicing our finning techniques. Periodically, he’d grab a buddy team and go to a separate area to evaluate their skills, such as the valve drill, removal and replacement of the mask, and use of the long hose in an out of air situation. All of this was to be accomplished while we were completely horizontal and suspended inches

above the silty bottom. Some of us were more successful than others. Our performance was video taped for critique that night.

As we sat in the classroom, eating some of the worst pizza on the island, we watched ourselves on the screen. Andrew's language was colorful and we learned that instead of the intended skills, we sometimes performed others, such as "humping the dog." Of course, this was not good and we needed to improve.

The next day, we were at Maeda Point. Maeda is noted for its 74 steps and a brief climb down a rock face to get into the water. Most of us were on doubles, which always adds to the joy of the climb. Once again, Andrew set up a course for us to traverse, but this time, we were subject to his "swooping down like a dark, avenging angel of death act," in which he creates problems such as manifold failure, valve roll-off, mask loss, etc. The idea is that a competent diver needs to deal with these difficulties efficiently without undue stress. Then he doubles them up, increasing the level of task loading. Chris, my buddy, and I had to deal with an out of air situation while I had lost my mask and return to the up line which was a good distance away and make a proper slow ascent. To be honest, we found these problems interesting, but not intimidating. The skills set in less than ten feet of water was more challenging.

On the following morning, we began training on the RB80’s. The RB80 is a nice, compact unit, with a diameter the size of an aluminum 80 and a length not quite as long. It is a "passive addition" semi-closed rebreather capable of handling all types of breathing mixes and depths. Gas addition is tied to the diver’s breathing rate. It is completely mechanical so there's no circuitry to fail. Water and electronics don't mix very well. If something does go wrong, the indicators are intrusive or intuitive like open circuit scuba. With closed circuit and active gas addition semi-closed circuit rebreathers, the diver may be unaware of problems due to no interruption of the breathing loop or being too hypoxic to respond to audible or visual electronic warnings.

After we assembled our units, we sat on the floor of the scuba lockers rental side and practiced valve drills over and over again. Then, Andrew would give us a simulated manifold malfunction and we had to correct the problem. The idea was to build muscle memory by repeating the movements necessary to complete the skill. It was a strain to reach the valve knobs there and equally difficult, I would later find out, in the water. The RB80 manifold is shaped like a narrow boomerang and the knobs aren’t as easy to reach as the ones on my doubles isolation manifold.

Back at Maeda, we began our training with the same drills used in the fundamentals class. Skills done hundreds of times on doubles suddenly became difficult with the rebreather. Conducting an out of air exercise while both divers maintained a perfectly horizontal attitude became a CF* when initially done on the RB80. I kept forgetting to turn the mouthpiece switch to open circuit when my partner gave the out of air signal. I tossed the block and hoses up and was confronted with a cascade of nitrox gushing from the mouthpiece. Luckily, I didn't flood the loop. From habit, I also exhaled immediately after removing the mouthpiece block, which sent me plummeting to the bottom. I was a klutz.

Buoyancy proved equally difficult. No longer did inhalations and exhalations control depth in the water. Accurate use of the inflator/deflator mechanism, as well as the dump valve on the wing was critical. It was frustrating to exhale and discover that I wasn't descending, or feel myself beginning to descend and find that a quick inhalation had absolutely no effect. As the course progressed, Andrew set up a vertical course wherein we were supposed to spend a minute at each 10 foot stop down and up to and from 70 feet. And he wanted you to stay in position relative your buddy and relative to the line. It was interesting.

During the rebreather training, the "avenging dark angel" reappeared about every other dive to create havoc, confusion, and challenges for the trainees. Not only did we have to deal with the specific situation, we also had to find the most opportune route back and ensure team integrity. If the out of air diver wasn't positioned correctly between the two other divers, we heard about it in the debrief. One of the more memorable situations occurred at Onna Point when Andrew signaled me to confront Chris with an OOA situation after Andrew had surreptiously rolled off his left post. Chris was visibly surprised when he put his necklaced alternate in his mouth and found one breath was all he got. So was I. I reached quickly to turn on the left post. So was Andrew. He had his long hose primary out and ready.

As we progressed to increasingly more complex levels of task loading, we started to experience a degree of success. Chris and I were able to negotiate the 70 foot ascent/descent course in the 13 minutes time frame required. Responses to out of air situations were executed without forgetting to switch to open circuit. We became more cognizant of the proper team response to the situation. Valve failures were dealt with quickly and efficiently.

Still, I continued to have difficulty reaching the knobs on the RB80's isolation manifold during the valve drills while remaining motionless and locked into a horizontal position. I practiced stretching exercises out of the water. We conducted valve drills at the beginning of every dive and every time we switched from open circuit to closed. Nevertheless, I felt that my arms were about to be wrenched out of their sockets by my straining to grasp the knobs. Finally, after loosening up the crotch strap a bit more, and inverting slightly, I was able to grab the damn things. But it wasn't fun.

The last dive of the course was at Maeda. It was designated as an "experience" dive, which meant the avenging angel had left the area and we could relax and enjoy ourselves. As we headed up the reef, for the first time, I began to like diving on the rebreather. The three of us were in essentially a line abreast formation, while Andrew wearing twin AL80’s, hung back and observed. As we swam almost effortlessly and silently, the reef seemed to be more alive. Our exhaust didn’t upset the quiet underwater balance. Fish didn’t scatter and flee at our approach. I found myself hovering among a school of barracuda, which seemed bothered not at all by my intrusion into their ranks. Shortly after turning the dive, we found a sting ray half buried in the sand. As we surrounded it from a distance of a few feet, the normally skittish ray remained calm watching us as intently as we watched it. Only when Andrew approached on his noisy open circuit rig was the spell broken and the ray fled down reef.

I put Andrew on a Tokyo bound plane early the day after our last dive. I then drove home intending to accomplish tasks that I had neglected during the previous week and a half. However, I made it to the couch and sat there most of the day watching the tube, having lost all motivation to do something productive. I was tired. No, I was exhausted.

For the first time in years, I had accomplished something in which success wasn’t certain and where I had to struggle each and every day to even receive a rating of adequacy. It had been difficult, especially for someone in his mid-fifties who was used to apportioning comfortable limits for stress and exertion. The strain was obvious, and was corroborated by the digital photos that were taken each day. It was like I had become a victim of an obscure accelerated aging disease by the end of the course.

However, there was also a real feeling of pride and sense of accomplishment. Prior to the fundamentals class, I’d been a "vertical" diver except while swimming. Now, I did everything from a horizontal position. At the start of the rebreather class, my buoyancy control with the unit was pathetic, but now I could slowly descend and ascend through the water column relying solely on my ability to add and release gas to the wing.

And if something went wrong, I was confident that I could handle the problem. After all, I had been through "Hell Week" with Andrew.

My wife told me not to worry about "vegging" on the couch. I had earned that right.

*CF - Ask any enlisted member of the U.S. Marine Corps for the meaning of this term.