Exploring the Deep Frontier

with the first

Electronic Rebreather 1968-70

Editor's note:  This is the third of a three part series on my experience of diving, marine science and underwater photography in the 1960's. The first part appears in issue #11 for Mar/Apr 2003 and the second in issue #12 for May/Jun 2003.


One should be careful with long held dreams.  They have a way of becoming reality.  Since my early teens I had dreamed of having my own boat and exploring remote reefs and islands.  In late 1967, at age 28, I was at last able to place an order for my dream.  It was to be a small long range well equipped twin diesel  steel research vessel.  A beam of 28 feet in a 64 foot length provided plenty of room,  a large fuel and water capacity and  exceptional stability in a compact shallow draft   vessel I could operate with minimal crew or even alone when necessary.

El Torito was named after the Spanish name for the cowfish (Lactophrys quadricornis).  Literally it means "little bull".  Both the fish and the bull references seemed apt.  For the next 20 years El Torito was to be my home and take me from the Caribbean to widespread explorations through the Western Pacific.

While El Torito was under construction development of the Electrolung came about through a chance meeting of John Kanwisher and I aboard Ed Link's diving research vessel Sea Diver in the Bahamas in early 1968. Ed was trying out his new diver lock-out submarine Deep Diver and had invited along several researchers with relevant interests. I was there to do some deep biological collecting and John was there to do heart rate/respiration measurements on divers using some new acoustical telemetry equipment he had developed.

Lock-out dives from Deep Diver were done using hose fed open circuit Kirby Morgan helmets. Gas for this purpose and to pressurize the lock-out chamber was supplied from a large high pressure sphere carried by the sub. The large amount of gas required for a single dive severely limited the number of dives which could be made and involved substantial cost and logistic considerations. The need for more efficient utilization of gas was clearly apparent.

It turned out that John and I had both been considering the feasibility of a mixed gas closed circuit rebreather using electronic sensors to control PPO2. We both knew in general terms what was needed but John wasn't a diver or a machinist and I didn't know that much about electronics. However, I had been diving for 15 years and had built a wide range of underwater equipment and John, in addition to being a physiologist, had invented the first polariographic oxygen sensor and held a dual appointment at Woods Hole Oceanographic Institute and Massachusetts Institute of Technology where he lectured on electronic instrument design.

When we returned to our homes John started putting together the sensors and control circuit and I started designing the hardware and finding or machining the components.  Six weeks later we both had our respective parts together. John sent me a bread board controller circuit and sensors.  I installed them and it and a few test dives showed that it indeed worked. The overall concept and design appeared good but there were of course, numerous details to clean up. The electronics for example were wire connected on a breadboard and the solenoid valve I had hand made using a solenoid scavenged from a battery operated cuckoo clock.

Although the prototype was put together quite quickly it was far from a "first thing which comes to mind" effort. Quite a few years experience and thought had led up to it so when actual construction began we both knew pretty clearly what was needed and how to do it.  Over the next few months we quickly followed with a cleaned up version using printed circuit boards, a proper miniature pneumatic control solenoid valve and sundry improvements to various details of the  mechanical design.

 A couple of years later, after we had  sold the commercial rights to the Electrolung to Beckman Instruments, I had the opportunity of working with a team of high tech engineers on improving the same device. The outcome was some further tidying up of details but no fundamental changes. The biggest problem was to prevent the creation of problems which didn't previously exist but could be introduced through changes made by specialists who were unaware of consequences outside of the narrow area of their expertise. The experience gave me a appreciation of both the strength and the limitations of specialist expertise as well as the importance of systems analysis in coordinating and integrating specialist input.

John Kanwisher was also on one of the advisory panels to NASA in connection with the Apollo program. Although he recommended using a mixed gas atmosphere in the Apollo capsule he was over-ridden by engineers who felt that monitoring the PPO2 was too difficult. John knew better as he had been doing it for several years in conjunction with his work on respiration but the engineers prevailed. The result was a fire which killed three astronauts after which they switched to a mixed gas atmosphere.

In late 1968 the first operational version of the Electrolung was ready to go and so was El Torito.  In November of that year I set out for Cozumel aboard El Torito with several new Electrolungs.  Over the next few weeks I conducted a series of dives culminating in a descent to 400 feet where I photographed and collected a new species of gorgonian. During the next two years I dived the Electrolung exploring the deep outer dropoffs of reefs from Cozumel to Belize and in various location in the Bahamas. This work involved the discovery of several  more new species of fishes and invertebrates.

 A story  in the August 1970 issue of  Skin Diver Magazine told the story of the development of the Electrolung and the September issue followed with a story by Paul Tzimoulis on making a 300 ' Electrolung dive with us  on "The Wall" off Fresh Creek, Andros Island in the Bahamas. My story, "Probing the Deep Reef's Hidden Realm", appeared in National Geographic Magazine in December 1972. 

Although development of the Electrolung was exciting, in itself it was just an interesting incident in a bigger, more interesting and more significant picture. Like most historical events, I suppose, what was happening didn't appear to the participants at the time so remarkable as it later does in the broader perspective of hindsight. The larger view what is taking place at any time tends to be somewhat obscured by the ordinary events of living. Except for rare instances whatever we are doing, however interesting and exciting it may be, tends to still feel like life, not like history in the making.

In retrospect however, I have come to realize that from the mid 1950s through the mid 70's something remarkable was taking place in diving. During that period it grew from the obsession of a small group of generally impecunious young people mostly in FL, CA, France, and Italy to a global industry catering to relatively well-to-do hobbyists. Remote tropical islands all over the world began to sprout airports and dive operations and diving became strongly oriented to travel to exotic locations. Though all this was in itself remarkable something truly unique was at the heart of what was happening.

For the first time in history humans could freely enter, explore and personally experience the oldest, richest, most beautiful and exotic communities in nature, tropical coral reefs. Coral reefs are truly special places. Nowhere else can one experience such an abundance and diversity of life. Nowhere else is it so colorful, exotic and so easily experienced at close range.

Diving on a reef is like a trip in a time machine to a time before humans existed and nature ruled in primeval pristine abundance. Fossils of many reef creatures from as much as 60 million years ago are essentially the same as those on reefs now. In fact some Pacific reefs have continuously existed as reefs for that period of time. Considering that our own evolution from ape to today's humans has all taken place in about 3 million years this is truly a vast span of time.  Sixty million years ago or even 5 million years ago on land you would find a world of creatures very different from today's animals but on reefs you would feel right at home surrounded by corals, fishes, and other creatures very similar to or even indistinguishable from those we see today.

For a biologist, being among the first to dive on reefs was an extraordinary experience. In a way it was a bit like landing on another planet. On nearly every dive you were going where no human had ever been before. The discovery of phenomena of life and strange and beautiful creatures whose existence we never even suspected was an everyday occurrence. At the time this kind of experience was so commonplace, tropic seas so vast and remote, and so few people were doing it, that it began to seem as if this was just the way things were and this kind of experience would continue indefinitely.

Already however, this era has become history. Although there are vast amounts still to be learned about the details and inner workings of reefs, undiscovered species are getting harder and harder to find and remote locations are becoming less and less remote. The experience of being among the first to explore the richest realm of nature has come and gone, not to be repeated.

On reefs, one niche still remains. Actually it is a really big one. The zone below 200 feet, down to the deepest limits of what you might call part of the reef community at about 600 feet, is still largely unexplored. Although it is not so rich in life as the shallower regions it is still quite rich and is an area about which we know very little.

As far as I am aware the only person on the planet regularly exploring this zone is Rich Pyle from Hawaii.  As well as making more deep free dives than anyone ever has before he is coming back with knowledge and specimens from every dive. What he is doing is a permanent contribution to knowledge which will stand long after any of today's diving records are broken and forgotten. I have never met him personally and am commenting only out of recognition of something exceptional.

Over the past 25 or thirty years advances in diving technology have been almost entirely small and incremental. The only real exception I can think of is the development of dive computers. It appears we are up against the realities of human physiology. With every increase in depth and bottom time the cost, complexity, effort, and risk increases exponentially while the return of useful achievement remains more or less linearly related to bottom time.

The future would seem to lie in other directions, especially robotics.  Here advances have been impressive and future development promises to become even more so. Already we are at a point where more and more functions previously requiring a diver can be effectively carried out by remote operated vehicles, ROVs . It is not hard to foresee that in a few years most of what we do at great effort and risk by diving can and will be done by an operator at a console. Currently increasing amounts of offshore oil and gas drilling is taking place in depths beyond the reach of divers with all operations at the wellhead being carried out by ROVs.  Even within diveable depths ROVs are taking over more and more of the tasks previously done by divers. 

If as a diver you find this kind of scenario uncomfortable, don't let it worry you. Long term prediction, no matter how well reasoned and seemingly inescapable, has a way of almost always being wrong. So much so that I have often wondered if beneath the facade of Newtonian certainty of our universe , somewhere in the iffy probabilistic realm of quantum mechanics, there is not something which dictates that the very act of prediction sets in motion forces which generate a different outcome. So if you don't agree with my prediction, the good news is that I may well have voided it by predicting it.

Fortunately, the real outcome is usually even more interesting than any of the predictions.

Rebreather Note:  Many dedicated underwater photographers are currently wondering about the pros and cons of  rebreathers.  The following from a recent post by myself to the Rebreather Discussion List may provide some thoughts worth considering.

"The endless debate over the role of design, error, and training in rebreather fatalities seems to involve more than a hint of denial.  That is, it won't happen to me because I don't use that unit, or wouldn't make such a stupid mistake,  or have been properly trained.  It also tends to obscure one overwhelmingly important fact.  All rebreathers are inherently dangerous. The overall fatality rate with RBs is about an order of magnitude greater than with open circuit and  with the latter the majority are beginners while most of those with RBs are "experienced" divers.

Regardless of design, RBs incorporate a variety of means by which through error, inattention or failure they can kill you.  Where the cause of accidents are known the overwhelming majority are attributable to operator error of a type that neither design nor training are likely to prevent.  Rebreather use demands good mechanical and instrument sense, meticulousness, multitasking ability, and  risk assessment judgment.

While design and training are important they cannot make up for inaptitude, carelessness, distractibility, or poor judgment.  Many very  capable and safe open circuit divers are simply unsuited for RB diving. Until we recognize and learn to assess the requisite human parameters of RB diving the harsh rules of natural selection will continue to be reflected in the mortality statistics.

Those who think that design and training will make them safe would do well to consider whether they really have the aptitude, focus and objectivity required.  Not being an anal retentive, schizophrenic, gearhead, nerd is not exactly a failing and being wrong about it involves a very big bet with dire consequences for sundry innocent parties."

If  going deeper or getting closer to some fishes is worth the expense, logistics, maintenance, attention, and risk of  rebreather diving only you can decide.  If in doubt give it a miss and spend the extra time saved in carefree diving with ordinary scuba.  You won't lose much in the tradeoff.

For a good general discussion on rebreathers see:

For more on Rich Pyle's work see: The Coral-Reef Twilight Zone