I find myself writing about this because no matter how much I think about it, it still just seems so extraordinary. ‘It’ being Mighty Mouse, aka Sara Campbell, the world free-diving record holder and the tester of our Supermarine watch. My brother, Giles, and I have been developing mechanical watches now for several years. Our background is predominantly flying and restoring vintage aircraft, but we also entertain an infatuation with all things mechanical. Many of our watches are inspired by this love, but also, by a desire to make something technically beautiful. The idea to produce our first diving watch (or marine watch as we call it) therefore presented an exciting challenge.

Aviation continues to play a huge influence in our watch development. We have just finished developing a watch in conjunction with an incredible British company called Martin Baker. Set up in 1922, Martin Baker supply fighter ejection seats to over 80% of the worlds air-forces and to date, have been responsible for saving over 7,200 fighter pilots, lives. The seats have to withstand the rigours of vibration, temperature extremes, G-forces, shock and many other external factors. Bremont was approached to make a watch that would undergo and withstand the same testing criteria as the seats. It has taken 18 months of development, and some very special innovation, but the watches should be available later this year.

This brief mention of Martin Baker is just to prove that our inspiration is still very much aviation even with our new marine watch. As a bit of background, one of the most inspiring aircraft for us is the Supermarine SB-6 Schneider Trophy sea-plane.  Built in the late 1920s and early 1930s, the SB-6 (the predecessor to the Supermarines most famous plane, the Spitfire) is one of a handful of aircraft that really did have a huge impact on aviation development. The aircraft ran off a mixture of gasoline, methanol and ethyl which made starting the 2300 hp engine quite exciting. On the 16th September 1931 the SB-6 established  a new airspeed record of 655 km/h.

Our love of the SB-6 led us to produce the first British diving watch in decades, the Bremont Supermarine 500. This will be a beautiful 500m marine watch with a sapphire bezel containing a lot of the aviation DNA, anti-magnetic Faraday cage shielding the movement, and our anti-shock movement mount, that we have developed over the years. There is an awful lot going on inside the watch, which from a nerdy, watch perspective, is pretty exciting.

Testing has always been a key part of any new Bremont model, and we were anxious to ensure that this watch was no different to other models that have been heavily tested in the field. We heard about Sara Campbell about 18 months ago. This British girl had just broken three free-diving records within nine months of taking up the sport. Naturally, we got in touch and over the last year and a half she has been taking our watches down to 100m on one breath, which is really quite incredible if you think about it.  You can test a watch as much as you like in the workshop, but taking it down to these depths (all our models have now been tested by Sara) is not only more demanding, but also much more satisfying.

While it was very interesting for us to see how our watches withstood these huge pressure changes, far more fascinating was how this 4 ft 11 woman was capable of diving to such depths on a single breath of air. Sara was competing at the Vertical Blue competition in the Bahamas in April, and it was here that she set a world record in the womens constant weight discipline, diving down 96 m with just one lungful of air, a wetsuit and a mono-fin to propel her downwards. The dive took her 3 minutes 36 seconds.

The way the competition works in the constant weight category is quite simple. There is a weighted rope that heads vertically downwards and the diver is attached to this rope to ensure they are heading in the right direction when there is nothing but darkness all around. Before the dive, the diver must state how deep they are attempting to go (this is to prevent divers pushing themselves too far), and then they dive down until they reach a ticket placed at the given depth (96 metres in Sara’s case). They must grab this tag and then make their way back to the surface. There are no inflatable devices to help the ascent, so the way down is only half the battle getting back the other, and more important, half. What amazed me is that because of the depths, there are no safety divers below about 30 meters (due to the length of time it would take to decompress from such depths), and so the divers really are on their own.

Sara sees free-diving as being one of the most natural sports around. The sport grew from the ancient traditions of pearl and sponge fishing, and dates from the time when humans has long known that the body can survive longer underwater than the medical profession would have us believe. It is this confounding of science that makes free diving so fascinating.

The mammalian dive reflex makes it possible for humans to dive to depths thought potentially fatal for the human body. This reflex is our body’s natural response to being in water. It begins the moment we put our faces in water and it stops once our airways are clear to breathe once more. As Sara dives vasoconstriction occurs this is where the veins and arteries in her peripheral circulatory system contract forcing blood to the core of her body and her vital organs (brain, heart and lungs). As she descends deeper an extension of vasoconstriction occurs this is called blood shift. As her lungs compress with depth due to the increasing pressure, the air space inside gets smaller. There is a limit to how small her lung can become before tissue damage occurs. Blood shift occurs when the capillaries inside the lungs get bigger and fill with more blood preventing lung damage and helping with efficient gaseous exchange.

As Sara returns to the surface the process is reversed. The greatest danger in free-diving is this final part of the ascent the last 10 metres or so. As the diver gets low on oxygen, the lungs are also expanding, and in order to do so they need to fill with gas. Oxygen is drawn out of the blood and into the lungs and if the diver is already very low on oxygen, it is usually this last reserve that maintains consciousness. The black out is the body’s final survival response. Upon registering very low levels of oxygen in the blood, the brain decides to protect itself and shuts the body down. This is where safety divers are crucial, as they bring the lifeless diver to the surface and lie them on their backs, where, in most instances, the diver starts breathing automatically.

This is actually what happened to Sara a day or two after she broke the womens record at 96 metres. Determined to be the first woman to reach 100 meters (the mens record currently stands at 108 metres), she went for the record. She made the dive, picked up the ticket, reached the surface and then blacked out for a few seconds. Blacking out, unfortunately, meant that the attempt didn’t count. Sara, with Bremont’s help, will be going for this depth again shortly.

All of this is very interesting, but what makes Sara so good, and how does she manage to beat competitors who have been training for years and years? I’ve asked her this question a few times and it seems to be a combination of a few things. Firstly, Sara has a lung capacity 25% greater than the average woman, which clearly helps. She is also a yoga instructor. When you head down into the abyss with nothing but darkness all around, you need to be of a certain mindset to ensure you don’t panic, and to make sure your heart rate stays low. Sara uses meditation as an integral part of her training and it helps her keep immensely relaxed and calm during a dive. Another, more unusual explanation, is the size of her spleen! When she descends and her organs compress, her spleen also compresses and injects oxygenated blood into her system (a spleen is capable of storing a lot of blood). Her larger than average spleen could therefore be one more string to her bow so to speak.

What is interesting about the free diving is that divers seem to get better with age. Unlike other sports where age is a definite handicap, due to the more advanced mental development and self-belief with age, Saras career in diving has only just begun at the tender age of 37. NICK ENGLISH