Surviving the World's Deepest Dives

[Music] the ocean is a magnificent inhospitable place cold dark and violent it is an environment that people have contended with frezz long as humanity has existed many have traversed the oceans surface but only relatively recently have we begun to grapple with the final frontier of the sea but deep as you descend deeper and deeper into the ocean the laws of physics are instantly and harshly working against you most of the visible light spectrum is absorbed within 10 metres of the water's surface and almost none penetrates below 150 metres even when the water is very clear and as you go deeper the temperature falls and the pressure quickly becomes immense every 10 metres adds another one atmosphere of pressure recreational divers can safely descend to 33 metres on the way down your ears have to be equalized constantly and slowly but surely everything becomes more and more blue as the other colors of visible light disappear nitrogen narcosis can start to set in and even at this relatively shallow depth the surface can feel distressingly far away but deeper than this much much deeper there is work to be done precise technical work that requires sharp concentration and hours of manpower working so far below the surface should be outside the realm of human capability and yet every day the ocean floor is occupied by men and bizarre suits carrying out extremely difficult work so how is it exactly that we can send people down to these depths to complete complicated tasks sometimes working underwater for hours at a time what science is involved in this dangerous but essential job that enables these divers to stay alive commercial divers work to maintain offshore oil rigs and pipelines completing tasks that require more precision and maneuverability than a remotely operated vehicle can manage divers are needed to flip flow valves both pipes together or clear debris the work is essentially heavy-duty construction that happens to be under the sea it's an isolated and dangerous job and often involves working underwater at depths of up to 500 meters there is danger in being so far below the surface relying on your hoses for your air supply heat and communications and dealing with heavy construction materials but much of the danger the divers deal with does not come from the cold dark deep itself but rather returning from it decompression sickness or the bends is a debilitating disorder that happens from a rapid decrease in pressure on the body causing gases that were dissolved in tissue to form life-threatening bubbles any diver has to be very careful to avoid this dangerous phenomenon but for divers working extremely deep and for long periods if left unchecked decompression sickness would be definitively fatal air is made up of roughly 78% nitrogen and 22% oxygen normally on the surface we simply breathe out the nitrogen that we inhale since our bodies don't use it but when diving at depth each breath taken contains many more molecules of oxygen and nitrogen than a breath taken at the surface due to the increased pressure and with all these extra molecules entering the lungs they begin to accumulate in the body as the pressure increases the nitrogen gas into solution and more and more of it dissolves into the body's tissues this dissolved nitrogen is luckily harmless in our bodies if we stay under pressure but when it's time to come back to the surface the problem begins as the outside pressure decreases during ascent from a dive the accumulated nitrogen forms bubbles in the blood and tissues this is because gas comes out of solution when pressure decreases just like when you open a bottle of soda and if these bubbles are too big or formed too quickly they can injure tissue or even block blood vessels the blood vessel blockage causes pain and in the worst instances death in regular diving this risk is mitigated by coming up to the surface gradually allowing the nitrogen to diffuse slowly out of tissue and be exhaled through the lungs avoiding the build-up of big nitrogen bubbles diving to 75 meters for an hour for example would require a five hour ascent to avoid getting bent and the longer the dive the more dissolved nitrogen has built up in the tissue and so the longer the decompression time needed for deep-sea divers working at depths much greater than this and for many more hours the amount of time it would take to safely ascend would be way too long to be feasible and on top of the deadly effect of decompression sickness nitrogen plays other tricks on the body nitrogen narcosis is a condition that hits many divers when doing deeper dives usually setting in around 30 meters at this step it can cause an alteration and consciousness basically giving you the feeling of being drunk it's usually not harmful in and of itself but slowed mental activity giddiness and overconfidence can lead to divers disregarding safe diving practices at 30 meters on a recreational dive the effects are kind of amusing and can be simply reversed by ascending a few meters but as you go deeper and deeper the effect can be debilitating and mental impairment may become extremely hazardous below 90 meters it can lead to hallucinations loss of memory or in consciousness which for deep-sea divers working on intricate and dangerous tasks could quickly become fatal scientists don't fully understand what causes it but believe nitrogen gas or any inert gas except helium and probably neon react with lipids or fat tissues which make up most of the brain causing an effect and so because of the tricky interaction between the physics of gases and physiology of the body for a long time deep sea dives remained out of reach but this all changed in the 1960s as NASA was launching its effort to put men on the moon the Office of Naval Research was working on their own otherworldly mission putting men at the bottom of the ocean in July of 1964 an odd-looking vessel was launched from the Navy's oceanographic research tower off the island of Bermuda where it sank to a depth of 60 meters 12 hours later for Navy divers entered the sea lab one ready to begin a unique 21-day experiment their assignment was to participate in the Navy's first extended physiological tests to determine how men can work freely and for long periods deep below the surface the primary mission of the Sealab project was to see if time-wasting dangerous daily decompressions while returning to the surface could be eliminated by providing a shelter near the dive location capped at a pressure equal to the diving pressure this would in theory allow the men to work for longer and at greater depths as I mentioned before when under pressure every breath you take contains more molecules of nitrogen and oxygen than on the surface and the extra nitrogen dissolves in your tissues but after enough time at a certain pressure the body can't absorb anymore and becomes fully saturated with it more time at that depth will not add any more nitrogen to the tissue and thus more bottom time will not add to the length of the decompression time because of this divers can stay pressurized indefinitely working multiple long dives while only needing one long decompression after days weeks or even months of time below the surface this type of diving was coined saturation diving and is much safer than making multiple short dives that each require their own lengthy decompression the dives can also be deeper and longer since decompression can happen in a controlled habitat however while decompression sickness is managed with this method it does not solve the problem of nitrogen narcosis nitrogen breathed at depth would still be incapacitating underwater or in the living quarters to avoid this problem saturation divers don't breathe normal air instead they breathe a gas cocktail called heliox which replaces most of the nitrogen in normal air with helium helium does not cause the narcotic effect that nitrogen does and is harmless to the human body decompression from a heliox saturation dive also requires less time than would be required with an air mixture that contains more nitrogen however breathing helium does not come without its own consequences and sounds exactly as silly as you would think [Applause] [Music] [Applause] and while amusing to those of us who don't have to deal with it for weeks on end it can become annoying and actually problematic it's hard to understand people over the communication systems with these voices so surface personnel often have to use a piece of equipment called a helium descrambler which electronically lowers the pitch of the divers voice after a series of Sealab experiments it soon became apparent that it would be easier and cheaper to monitor and support the divers if the pressurized living quarters weren't actually at the bottom of the sea but instead onboard the dive support vessels and kept at pressure mechanically divers enter the chambers and the blowdown begins slowly and carefully the pressure increases to match the pressure they will experience at working depth after around 72 hours the divers bodies become saturated with the inert gas to get to the sea floor divers exit their pressure chamber habitats through an airlock and enter a diving bell which is also pressurized the diving bell is then lowered to the required working depth and the divers exit the diving bell into the cold dark water to work once the divers have finished their shift they re-enter the Bell which is hoisted back to the surface and the next shift can begin and while physically close to the others aboard the dive support vessel they may as well be in space the general rule for desaturation is 24 hours for each 33 meters of pressure so it can take days to decompress from a deep dive and rejoin society if done carefully and if there are no catastrophic equipment failures saturation diving can be done safely however the divers have to remain in a pressurized environment for the duration of their work time which can be as long as three weeks or more this means living in very close quarters with other divers with no privacy whatsoever mentally and physically it is extremely taxing and while mostly safe due to advancements in protocols and technology it is not without its dangers if an airlock fails the pressure would explosively decrease and bubbles would rapidly form in the blood basically boiling it bodies can be and have been shot out through any opening no matter how small it is immediately and gruesomely fatal and even with rigorous safety protocols in place decompression is still hard on the body and still comes with a lot of danger when undergoing g saturation divers report joint pain headaches and shortness of breath and these symptoms are unfortunately similar to the first symptoms of decompression sickness experienced divers know the difference but if any diver thinks they may be suffering from the bends the whole team will have to start the decompression again the only cure for early signs of decompression sickness is to return to higher pressure saturation diving is not for the faint of heart there is an ever-present sense of danger exiting the diving bell and entering a pitch-black underwater world is enough to make anyone squeamish and the days and weeks on end spent and confined quarters would be enough to make most people go mad but what if there was a way to eliminate the need for these claustrophobic pressure chambers what if there was a way to get rid of the risk of the bends and lengthy decompression times all together in part two of this video I will explore one of the craziest concepts in modern science so strange that it sounds like sci-fi liquid breathing it flips everything we just discussed about the human body in a deep water environment on its head and could revolutionize diving medicine and space travel as we know it pushing the limits of the human body is something that people have been doing for as long as humanity has existed flying climbing or diving we can't seem to resist the pole of extreme environments deep-sea divers certainly push these boundaries and breathing liquid could one day allow these crazy people to go even deeper if you like learning about these extreme pursuits then you should check out the human limits documentary series on curiosity stream curiosity stream is a streaming platform that has thousands of high quality high budget documentaries and the human limit series highlights people with extraordinary skills that go beyond what is usually deemed humanly possible the physical masters episode is particularly interesting and investigates the life of a free diver with extraordinary lung capacity a woman who climbs sheer ice Peaks and a blind man who sees through echolocation among other people with super capabilities and if you're a fan of educational content and looking for more quality things to watch during your quarantine then this is the perfect time to sign up because a subscription to curiosity stream and now comes with a subscription to nebula nebula is a place for top educational content creators like polyphonic Wendover productions and our other channel real engineering can create videos freely without worrying about the YouTube algorithm or D monetization it's a place where we can upload our content ad free and also experiment with original content and new series the original content is my favorite part of nebula shows like Tom Scott's game show money where he pits a bunch of youtubers against each other in psychological experiments or real engineering logistics of d-day series which has a new episode out today about the aerial landings that helped make d-day s so if you sign up for curiosity stream at curiosity stream comm slash real science you'll get a subscription to curiosity stream and a subscription to nebula for a year for just $19.99 by signing up you're not just supporting this channel but all of your favorite educational content creators thanks for watching and if you would like to see more from me the links to my Instagram Twitter and patreon are below [Music]

Channel: Real Science

Views: 357,939

Rating: 4.9246755 out of 5

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Id: Bmy8hqYvEyw

Length: 15min 30sec (930 seconds)

Published: Sat May 30 2020