If you think that scuba diving is all about attaching
an oxygen tank in your back and breathing through it
with the use of a regulator, then you are wrong.
There’s a lot more to scuba diving than that. In fact,
pure oxygen is never used in scuba diving, especially
on deep sea diving.
In recreational diving, air is commonly used and not
pure oxygen as most people assume. Air is basically
composed of 70 percent nitrogen and 30 percent oxygen.
However, nitrox mixes are now being used a lot more in
recreational diving as it decreases the chances of
Although nitrox is still composed of nitrogen and
oxygen, the oxygen concentration is a lot higher than
air. This will reduce the risk of nitrogen sickness or
bends, but it trades off depth. The more oxygen there
is in your scuba diving tank, the shallower you are
allowed to dive.
So, just why is pure oxygen not used in deep sea
diving? This is because of oxygen toxicity. As you go
deeper underwater, the pressure increases and oxygen
toxicity becomes a factor. So, by reducing oxygen in
the air you breathe, you will be able to go deeper.
However, by doing so, you will also increase the
amount of nitrogen in the air you are breathing which
can result in nitrogen narcosis when you go deeper as
well as nitrogen sickness or the bends.
You may wonder how deep sea divers go deep underwater.
The answer to this question is trimix. Trimix is a
special air mix designed for deep sea diving. Trimix
is composed of oxygen, nitrogen and helium hence the
Helium is used because it reduces the proportions of
nitrogen and oxygen. This means that because the
oxygen is reduced, it will enable the diver to dive
deeper. And, because nitrogen is reduced, the diver
will not experience nitrogen sickness or nitrogen
The great thing about helium is that it can be
breathable under pressure and it has very little
narcotic effect. Because of helium’s low density, it
reduces breathing resistance at depth or at pressure.
Also, helium does not enter slow tissues as readily as
nitrogen, which causes the bends.
The only disadvantage of helium is that it conducts
heat 5 times faster. Also, during descent, deep sea
divers suffer from a condition called hyperbaric
If you become a deep sea diver, you will learn about
the different variations of trimix. Some will be named
trimix 10/70 and etc. If you come across with trimix
10/70, it will mean that the gas inside the scuba
diving tank will be composed of 10 percent oxygen, 70
percent helium and 20 percent nitrogen. This kind of
mix is suitable for dives up to a hundred meters or
These are the things that you have to remember about
trimix. As you can see, deep sea diving is not as
simple as it may seem. There are so many aspects in
deep sea diving that you have to be aware of and one
of them is the gas used for breathing.
So, before you don your scuba diving gears and you
plan on going very deep, keep in mind that deep sea
diving is a specialty course that one needs to take
before they undertake dives like this. Deep sea diving
is different from recreational diving. It takes years
of training and a lot of discipline.