People have been scuba diving for fun for a little over sixty years. During this period, statistics show that for an experienced diver in good physical shape, using a single cylinder of air, diving in perfect conditions and staying within no-decompression-stop limits, 130ft (39m) is an acceptable maximum diving depth.
Some divers, however, will always want to go beyond the limits and may believe that all they need to defy the limits is courage.
Unfortunately, this is absolutely NOT the case.
The limits to deep scuba diving on air have nothing to do with bravery. The limits are physiological, rather than psychological, they apply to all of us and relate to what happens to our bodies and minds when we breathe air under pressure.
Air contains oxygen, which is a good thing because oxygen keeps us alive. However, paradoxically, too much of this good thing can cause the brain and body to malfunction, the deeper you dive the more oxygen you take in with each breath and the more you are at risk of a seizure.
What also happens as you dive deeper is that the air you breathe becomes denser and it becomes harder to breathe efficiently. This inefficiency leads to a build up of carbon dioxide in your body and that can bring on irrational anxiety. You know those stories about divers panicking and shooting to the surface from depth? Blame excess carbon dioxide.
If that was not enough, the deeper you go, the more the gases in your body, particularly nitrogen, develop something referred to as anaesthetic potential or narcosis. The impact of this on the brain is similar to alcohol.
So, in a nutshell, diving deep on air gives you oxygen poisoning, makes you prone to panic and gets you drunk. None of these is anything you want happening to you when you are far below the water’s surface and, in combination, they can be fatal.
Fortunately, today’s sport divers with deeper thoughts have a viable option to air. Every day, many people dive safely well beyond 130ft (39m) using helium-based gas mixtures.
Helium is light and inert and by including it in your breathing mix, you reduce your exposure to the factors that make air so dangerous at depth.
Be aware helium is expensive, as is good deep diving training, and you will need new equipment.
But, if you are an experienced, self-reliant and disciplined diver, and a team player, it may be for you. Ask your instructor or dive shop for more information. Most training agencies offer mixed gas courses.
