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Four thousand people have climbed
to the top of Mount Everest,
and 562 have been to space,
but only seven have made it to the bottom
of the Mariana Trench.
Are you ready to join that exclusive club?
Almost 11 km (over 36,000 ft)
below sea level,
it's the deepest location on Earth.
And getting there is not going to be easy.
Not only will things get cold
and dark very fast,
but you'll also be facing a deadly amount
of water pressure.
The water pressure
at the bottom of the trench
is over 1,100 kg/cm2 (16,000 lbs/in2.)
That's about 1,000 times
the pressure you feel at sea level!
With extreme conditions like these,
how has anyone made it to the bottom
and lived to tell the tale?
You would never make it to
the bottom of the ocean
without any equipment,
because you would run out of oxygen,
and your body would be shut down
by the pressure underwater.
So if you want any chance
of surviving this journey,
you'll need some sort of capsule
to bring you safely to the bottom.
How will you know what your capsule will need
to bring you to the bottom
of the Mariana Trench safely?
Let's take a look at two capsules
that have already made the journey:
the DSV Limiting Factor
and the DeepSea Challenger.
About 70%
of the Deep Sea Challenger's
volume is made up of something called
syntactic foam.
Syntactic foam
is the only floatation material
that can withstand the incredible pressures
in the Mariana Trench.
It's made up of millions of
hollow glass microspheres
suspended in a paste-like substance
called an epoxy resin.
Not only does this material have the strength
to withstand the constant pressure,
it also has the low density required
to keep the capsule buoyant.
If you didn't have this sort of protection,
you'd fall victim to the high
pressure levels pretty quickly.
The pressure from the water
would push in on your body,
causing any space
that’s filled with air to collapse,
including your lungs.
At the same time,
the pressure from the water
would push water into your mouth,
filling your lungs back up again
with water instead of air.
It's one thing to be able to make it
down to the bottom of the Mariana Trench,
but it's even more important to
be able to make it back up to sea level.
The DeepSea Challenger
has 450 kg (1,000 lbs) of steel weights
attached to either side of it
to ensure that it will sink to the bottom.
And then,
whenever you're ready to return
to the surface,
you can simply release the weights.
But what if you encounter
some sort of emergency?
Well, If there is a power failure,
the weights will drop automatically.
And if you have a support
team at the surface,
they can command the weights
to drop as well.
There is also a special wire
that attaches the weights to the sub
that will corrode after
11-13 hours in seawater,
just in case.
Your submarine capsule
is a sealed container that has
a limited supply of air.
If you want to keep that air breathable,
here are two main things
that need to happen.
For one thing,
the oxygen has to be replenished
as you use it.
If the percentage of oxygen
in the air falls too low,
then you're going to suffocate.
Also, the carbon dioxide
needs to be removed from the air.
If the concentration of carbon dioxide rises,
it will become toxic.
The DSV Limiting Factor's
air supply consists
of a rack of oxygen cylinders,
and a system that operates
like a small planet.
The carbon dioxide you exhale
into your capsule
is removed by devices called
carbon scrubbers.
They clean the air,
allowing you to breathe it again.
Basically, you would be breathing
the same air over and over again.
This gives you an oxygen supply that will
last for an impressive 16 hours,
along with an emergency backup
that will last an additional 96 hours.
When you make your journey down
to the depths of the ocean,
you're going to be relying
entirely on battery power,
so make sure you've got a lot of it.
The DeepSea Challenger
has about 70
bread loaf-sized battery packs
inside oil-filled
plastic boxes mounted into the sub’s sides.
The batteries are spaced
just far enough apart that
they won’t be disrupted when
the foam structure that they sit in
shrinks by about 1 percent
under the ocean’s pressure.
Having a lot of batteries
isn't just important for the obvious stuff,
like controlling the ship.
There are also dedicated battery systems
for search and rescue purposes.
For example,
one battery system
is completely dedicated to powering
LED lights that can
assist a recovery team
trying to find the capsule when it
returns to the surface.
So there you have it.
Surviving a trip down to the Mariana Trench
is pretty easy,
as long as you can afford a fancy submarine.
Some companies are even
starting to bring tourists down there.
And don't worry.
If you're scared of getting
trapped underwater,
we've got just the video
to help you calm those fears.