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Creating Underwater Images while diving a Poseidon Rebreather

Creating Underwater Images while diving a Poseidon Rebreather

Text and photography: Rui Guerra

I would like to begin with a collage and descriptions of some of my favorite images taken while diving my Poseidon MKVI Rebreather, followed by my story of how I evolved into a rebreather diver. 



Diving under the fill station of the dive center in the mangroves, the water was not as clear as in the coral reefs offshore. But it did pay off just to see the big school of fish that the dive guide had told me about.



This grey reef shark had made several very close passes by me, perhaps trying to understand if I were an already dead diver, since I was not emiting any noise or bubbles. We can see the exaust bubbles of other open circuit divers in the background, who did not get to experience the sharks getting nearly this close to them.


Without the noise produced by air bubbles, big groupers are far more curious and sometimes you can touch them with the camera's dome port.



Taking pictures without air bubbles while pointing the camera directly towards the surface is always difficult, especially in clear waters and at depths close to the 40 meters, like in this case at Azores Islands...unless you use a rebreather.


Cave diving photography is perhaps one of the situations where the great advantage of a rebreather like the MKVI is more noticeable. Its small size allows you to move in tighter areas and at the same time allows the photographer to take along additional image equipment, as in this case, where I took multiple remote strobes to illuminate the large gallery.


If you think that a rebreather is only useful at sea in deep dives, think again! This freshwater snake was photographed in a calm zone of a river that was less than 1 meter deep. It was really difficult to remain completely underwater, still and in complete silence. I was able to do it with my rebreather. The snake stopped a moment to look at me, I took the shot, and then it went on his way, passing under my body!


The machines room of the corvette "Oliveira e Carmo", a wreck near the southern coast of Algarve in Portugal, lies at about 30 meters deep. Everywhere there is sediment that raises at the slightest touch, reducing visibility drastically. To conveniently illuminate the huge engines, I had to put several strobes fired by remote cells. It was a long and painstaking work, only possible by the absence of bubbles and prolonged bottom time without mandatory decompression.


Working alone in this cavern while using the Poseidon MKVI allowed the school to approach at a reduced distance of my fisheye lens. As I slowly changed position, remaining inside the cave for more than half an hour, the fish always remained undisturbed and often approached at a touch distance.




Monk seals are very rare and near extinction, but in Portugal, in Madeira islands, we have a small population of a bit more then 20 individuals. Working with a special permit of the Natural Park Services, I've stayed there several days, trying to make some images of these beautiful animals. On one occasion, one of the females became very curious about my "big eye" dome port, probably because she saw her own reflection.


My Journey into Rebreather Diving and Underwater Photography

From an early age the sea has always been present in my life, with its incessant murmur. Every year my holidays were spent near it, camping for several weeks at various locations along the coast of Portugal, in more or less wild areas almost untouched by man.


My father’s hobby was angling from rocks, and when I was still young I began to accompany him in this activity that provided much of the food for our family during the summer weeks. When I was 13, I tried wearing a diving mask and peeking into the small pools between rocks formed by the receding tide. Even today, after more than 30 years, I still remember that day like it was yesterday! Small fish swimming among small algae and anemones. Crabs, shrimp and octopus filled every hole in the rocks, in very clean and alarmingly cold water.


Immediately I got the strong impression that it was there, below the sea surface, that I wanted to spend the rest of my life. This world, full of life and lit by a magnificent sparkling light, always exerted a powerful attraction on me.  I began to spend several hours every day, hovering on the surface with my face dipped in the water, exploring the underwater world with a happiness difficult to describe in words. In my head, I was an explorer, adventurer, and diver, following the footsteps of the famous Jacques Ives Cousteau, although in reality I was no more than a kid wearing a t-shirt and shorts, with an old rubber mask, shivering in the cold Atlantic’s waters.


The following 13 years were spent diving exclusively in apnea, where each piece of equipment was bought gradually, after arduous months of work during the school holidays. Summer or winter, with calm or rough seas, every week I spent several hours swimming long distances with my rubber fins and snorkeling in this wonderful world. I am sure that my personality was ultimately shaped by the sea, who taught me even as a teenager to be prudent and make decisions thoughtfully and quickly. At that time, few people practiced this type of activity in Portugal and the communication between them was difficult, so I dived mostly alone, gradually learning from my mistakes and having to get out of some more complicated situations. 


In 1991 my sister decided to offer me a small amphibious camera, and shooting underwater quickly became my main objective. I ended up spending some years practicing photography in apnea, until 1995 when I took my first scuba certification course so I could spend more time underwater and increase my range of action. However, there were two negative things in this type of diving that made me feel as if somehow I were downgrading in relation to snorkeling. One was the sound of bubbles released, which prevented me from hearing the various sounds of the underwater environment and seemed deafening to me as I was used to diving only in apnea.  Those bubbles also ended up chasing away the fish in many situations. The other negative of scuba was the short time duration of each dive, when I was used to spending several hours diving in apnea each day. That is, I was spending more time at depth, but much less in contact with the sea in each diving day, which was not so great.


Even before I started scuba diving, I had already avidly read all the books written by Hans Hass who was a true pioneer, and his adventures with cameras within handmade housings using home-built rebreathers were an inspiration. These and other stories left me dreaming about a system that would allow me to extend the duration of my underwater incursions, with total silence, as I did while diving in apnea. 


In 2009 the distributor of Poseidon in Portugal and technical diving instructor, João Neves from Submate, came to me and said, "Rui, I have the ideal rebreather for you!", everything was about to change for me. Years before he had been my instructor in a semi-closed rebreather that, although it was a good experience, I ended up not buying it because it had many limits to me. Now the Poseidon Discovery MKVI that was presented to me at a dive show, with its compact size and low weight, electronically controlled closed loop and CE certified, seemed to me to be too promising to be ignored. I decided to take the leap, now with the prospect of much longer dives and in complete silence again.


After almost 6 years since I used the MKVI for the first time and more then 500 hours spent underwater with it, I am convinced that many images were only possible due to the use of this equipment. The advantages of diving with a rebreather such as the Discovery MKVI are many and varied, some more obvious than others, from the greater respiratory comfort, reduced heat loss through respiration, automatic operation, silence with no bubbles, to a much greater diving autonomy. This increase of autonomy allows one to spend a weekend in a remote place and do 4 dives without refilling anything. So I can fill the car with imaging equipment, without having too much space occupied with extra scuba tanks.


This huge increase of autonomy with a small footprint system, eventually also lead me into the world of cave diving, where the absence of bubbles also become a very important factor to be able to photograph and film in this environment.


But even during a simple dive at a reduced depth, the mere absence of bubbles is great while using a fisheye lens and frame toward the surface. Gone are the days when I had to hold my breath (against the rules of diving ...) for shorter or longer periods, waiting for my own bubbles to reach the surface, and not to be recorded in the image.


Do I find that rebreather diving has any disadvantages? Yes, although in my view they are almost negligible compared to the benefits. Being a little more time consuming to assemble, it is necessary to provide some additional time for the preparation of the rebreather, and of course greater care. After the dive, some additional time is also needed to flush the system, but with practice we ended up greatly optimize this task, and it is possible to finish it soon after the other open circuit divers. Despite these small disadvantages, there is nothing too complex or too difficult, and rebreather diving is perfectly accessible to any average diver with the necessary certification. 


During the dive, it is recommended that you pay attention to your paddle, which is a computer synched into the rebreather. A regular look at the partial pressure of O2 and completing the security checks underwater allows me to free my mind to concentrate on image capture and to study the behavior of my subjects.


It’s during the dive that the change is more noticeable and still is for me an extraordinary evolution. The complete silence, broken only occasionally by the soft sound of the injectors maintaining the oxygen level, make the Poseidon MKVI and SE7EN as close as possible to the silence I experienced diving purely in apnea. And this silence, when complemented by slow and gentle movements of the body, makes me almost "invisible" to most of the inhabitants of the underwater world, who find me completely harmless after a couple of minutes if not right away. It is not uncommon large schools of fish envelop me completely at short distance, or an animal continues chasing its food as if I were not there. This true harmony and closeness of marine life has become apparent to me and is undoubtedly a great advantage in capturing underwater images of wildlife, whether photographs or video. Since the consumption of respiratory gases is extremely low, it is possible for dives to last several hours on a rebreather, which opens the door to a completely different world where animals, light, and events are changing in front of our eyes, as if we were in the cinema watching a feature film.


I stopped having to return to the surface because I was running out of air in the tank. I stopped having to abandon a good photo opportunity because I had to save gas to make the return back to the boat. I stopped having so many limits that steal my pleasure and symbiosis with the marine environment. Now, free from all this, I return when I want, I return when the mind and the soul are already full of unique experiences and sensations. I enjoy the freedom I feel when I dive with my rebreather, and dream about the great underwater adventures of the pioneer explorers, in a world full of life, bathed in a wonderful light that invites me to stay more and more ...


Rui Guerra

Underwater Productions