
Two days in an underwater cave running out of oxygen - Luc
http://www.bbc.com/news/magazine-40558067
======
benzofuran
When you're learning to cave dive, one of the first things that you learn is
that you may very well die in there.

Most of the training focuses on systems, skills repetition, and understanding
and using redundant systems - folks getting into cave diving typically are
already extremely experienced divers who if anything need only some minor
skill tweaks - most cave instructors will not take on students who don't
already have significant open water technical diving experience (multiple
tanks, mixed gas, rebreathers, decompression, wreck, etc).

A running joke is that the lost line drill (where you're placed intentionally
off of the guide line and have to find it without a mask/light/visibility) is
the most punctual cave task you'll ever do - you have the rest of your life to
get it right.

Here's a few good books on it (non-affiliate links):

Caverns Measureless to Man by Sheck Exley (the father of cave diving):
[https://www.amazon.com/Caverns-Measureless-Man-Sheck-
Exley/d...](https://www.amazon.com/Caverns-Measureless-Man-Sheck-
Exley/dp/0939748258)

The Darkness Beckons by Martyn Farr: [https://www.amazon.com/Darkness-Beckons-
History-Development-...](https://www.amazon.com/Darkness-Beckons-History-
Development-
Diving/dp/1910240745/ref=zg_bsnr_290109_1?_encoding=UTF8&psc=1&refRID=Q1DCCDZ0MMB4N2SCBYBQ)

Beyond the Deep by Bill Stone (the Tony Stark of cave diving):
[https://www.amazon.com/Beyond-Deep-Deadly-Descent-
Treacherou...](https://www.amazon.com/Beyond-Deep-Deadly-Descent-
Treacherous/dp/0446527092)

The Cenotes of the Riviera Maya by Steve Gerrard (patron saint / mapper of
Yucatan caves): [https://www.amazon.com/Cenotes-Riviera-
Maya-2016/dp/16821340...](https://www.amazon.com/Cenotes-Riviera-
Maya-2016/dp/1682134016/ref=tmm_pap_swatch_0?_encoding=UTF8&qid=&sr=) This is
more of a map and explanatory notes but gives great insight into the
complexity of it. Currently there are 2 systems that almost all cenotes are
part of in the Yucatan, and there's some really interesting work going on
trying to link the two. Current work is going on at about 180m depth through a
number of rooms at the back of "The Pit", and there are multi-day expeditions
going on trying to find the linkage.

~~~
enimodas
I would recommend this well written article:
[https://www.outsideonline.com/1922711/raising-
dead](https://www.outsideonline.com/1922711/raising-dead)

It's the story about the diver David Shaw and his attempt to recover the body
of diver Deon Dreyer in one of the deepest sweetwater caves on earth. A bit of
a read but well worth it.

~~~
idlewords
This is not cave diving, though. It's a very deep sinkhole, but with a clear
path to the surface. The risks in these dives are related to extreme depth,
not to the overhead environment.

That said, it's a terrific article.

------
curtis
Cave diving is one of those things that I am happy to only experience
vicariously through the stories of others.

~~~
narrator
Or you can watch Youtube vids like this :

[https://www.youtube.com/watch?v=WtlwoX1YEmg](https://www.youtube.com/watch?v=WtlwoX1YEmg)

This has got to be the scariest video on Youtube in which no harm comes to
anyone.

~~~
dotancohen
> This has got to be the scariest video on Youtube in which no harm comes to
> anyone.

Off topic, but here is a viable contender:
[https://www.youtube.com/watch?v=hFMHjDqHL_Y](https://www.youtube.com/watch?v=hFMHjDqHL_Y)

There are videos of higher towers, but I believe that this video is the most
thoroughly annotated one.

~~~
freeflight
That's a real classic! A not as high, but way more reckless version is this:
[https://www.youtube.com/watch?v=sFUcxnvAeMc](https://www.youtube.com/watch?v=sFUcxnvAeMc)
Guaranteed to induce acrophobia.

~~~
arcticfox
I really hope that guy practiced repressing the instinct to lunge at a bad
throw when juggling. Extremely rare occurrence with such a simple pattern, but
ooph!

I feel like any of Alex Honnold's ropeless climbs deserves a link too, for
example:
[https://www.youtube.com/watch?v=Phl82D57P58](https://www.youtube.com/watch?v=Phl82D57P58)

------
gregorymichael
Did a sensory deprivation tank for the first time a few weeks ago. An hour was
tough. Hard to imagine 60, with the added doubt of "you may never get out of
here."

~~~
pmoriarty
I find "sensory deprivation tanks" (aka "floatation tanks") to be rather
relaxing, and would have no problem spending many hours inside.

Now, being in a cold cave with a dangerous CO2/O2 ratio, exhausted, suffering
from hypothermia and fearing for my life.. that doesn't sound like so much
fun.

------
biggc
> He realised the water at the surface of the lake was drinkable

Can someone explain this phenomena? How can the water in a sea-cave become
potable?

~~~
titanomachy
I'm not familiar with Mallorca's hydrogeology, but I've done some cenote
(cavern) diving in Mexico's Yucatan peninsula. The caves are inland, but sea
water infiltrates through the porous and channel-filled rock. The water nearer
the surface is rainwater.

The narrow region where freshwater and seawater intermingle is called the
halocline, it creates a cool optical distortion which reminds me of the "oil
paint" filter in photoshop.

~~~
stingraycharles
This probably is a stupid question, but wouldn't the salty seawater be lighter
than the rain water, and thus be at the surface ?

~~~
cr1895
Salty water is quite literally more dense than fresh water. Average seawater
is 1025 kg/m^3, pure water is nominally 1000 kg/m^3.

Somewhat related video: dense brine that doesn't freeze in Arctic sea ice
sinks rapidly through liquid seawater below

[https://youtu.be/WyWn1XJ9kTE](https://youtu.be/WyWn1XJ9kTE)

~~~
stingraycharles
Oh geez, you're absolutely right, I don't know what I was thinking. I probably
needed my morning coffee.

~~~
x2398dh1
It's OK, stingrays like you aren't expected to know about polar regions and
super cold water.

------
fit2rule
I'm quite surprised at the detail that the rescuers attempted to drill into
the cave from above in order to provide supplies .. is anyone familiar with
the depth of the cave pocket? This seems like a surprising choice to make
given the logistics - but I guess a safer one, in the end .. assuming one has
a drill system available and the depth is not too great.

~~~
avh02
to follow up on depth (not just from a difficulty point of view), if care
isn't taken - i'd assume that once there's a pathway to the surface, the water
pressure would push the air out and drown him.

I also assume they're experts who know what they're doing, but at the same
time, I guess there'd be too many unknown unless there was some established
air-tight drilling technique specifically for this type of scenario?

~~~
fit2rule
To be honest, its a fascinating scenario which leaves many questions. I'm
going to have to ask my geology friends if there is such a thing as an air-
tight drilling technique that would not have resulted in the scenario you
describe - google-fu doesn't seem to produce results - but I imagine there
might be some sort of air-tight sleeve that can be used at the head of the
shaft, which may as well be rather thin diameter for this scenario, after all
..

What I'm curious about is whether these cave-divers used this procedure,
because they were prepared for it in some capacity. I mean, they managed to
start - and then abandon - the idea, in a few hours.

~~~
benzofuran
A lot of us cave divers work in other areas as well - I'm an engineer in Oil &
Gas - a lot of other folks I know are either scientists or engineers. This
sort of activity appeals to us for some reason.

You described a blowout preventer
([https://en.wikipedia.org/wiki/Blowout_preventer](https://en.wikipedia.org/wiki/Blowout_preventer))
by the way :)

Many cave systems are quite shallow, and while I don't know the details on the
one there in Mallorca, by the size of what's described it was probably above
the water table even though there likely wasn't a free-air connection to the
surface.

~~~
fit2rule
Thanks for the BOP reference. :)

Terrific balls, you cave-divers! Definitely not for me .. though the stories
do delight, and sometimes .. terrify.

------
ljf
Does anyone know any more detail about their plan to drill down to him - and
is similar rescues have been preformed this way? I'd be interested if the air
he was breathing was 'trapped' and if drilling down would release it, and
drown him, or if the air had a slow route in and out of the pocket he was in.
Fascinating stuff.

------
j9461701
I might be speaking out of line, but taking on these kinds of risks with young
children at home seems kind of selfish. The fact that he went back into the
same cave that nearly killed him only a month later...almost as if to say:

"I would rather my kids grow up without a Dad than live without my adrenaline
fix"

I am neither a father or a cave diver though, so I might be missing a piece of
the puzzle. Would either groups of people care to comment?

~~~
aasarava
Or maybe what he's saying is, "I would rather my kids learn that they should
explore and enjoy the world, rather than never take any big risks."

There are a lot of parents in the world. Once you start judging them (for
actions other than abuse and neglect), you very quickly realize how limiting
that is. Do we need to look down upon astronauts who have children? What about
pilots? People who travel for work for days or weeks at a time? Someone who
commutes an hour to work each way in a car that has a poor safety rating?

The good news is that once you become a father, you'll get to decide (possibly
with a partner) what the acceptable level of risk is for you and your family.

~~~
rdtsc
Given the choice of having a father at home or have one dead in cave but
famous for exploring cool places I don't think it's hard to guess what most
children would pick.

> The good news is that once you become a father, you'll get to decide
> (possibly with a partner) what the acceptable level of risk is for you and
> your family.

That's a obvious. What I think is being questioned is if they made a good
decision. In other I can freely decide not to strap my kid in a car seat but
that doesn't mean I won't get a ticket or my child won't be seriously injured
or worse in a car accident.

~~~
pragone
> Given the choice of having a father at home or have one dead in cave but
> famous for exploring cool places I don't think it's hard to guess what most
> children would pick.

In all seriousness, I do have a hard time guessing which one most children
would pick. I can see reasonable arguments made on either side. Personally, I
think it would be far more inspiring to have a father who died pursuing his
passion, then one who gave it up to stay at home.

~~~
jonahx
If you just asked them, in all their ignorance, you're undoubtedly right. If
you asked the children who chose the adventurous dad _after_ he had died
pursuing his passion, nearly 100% would trade the world to reverse that
choice.

~~~
curun1r
Your hypothetical survey method has a literal survivorship bias (and a
statistical one...you're not asking the children of parents that took risks
and didn't die). Looking at risk the way you're looking at it is a recipe for
wasting your life. The better way to think of it is like the way that poker
players look at their decision making...don't be outcome oriented. There's a
logical, statistical way to do this and it's called the micromort. 1 micromort
equates to a 1 in 1 million chance of death. Each activity that has been
engaged in widely enough to be measured will have a micromort value and, while
the math is a bit more complicated, they mostly just add up. Just because he
engages in an exotic activity that carries some risk, doesn't mean he's being
reckless.

Put another way, would you say a father that chooses to drive a 2 hour commute
(each way) per day is being reckless? No doubt you can find countless children
who lost a parent in an auto accident who would tell you they would have
wanted their father to have a shorter commute and still be with them. But
since driving is a familiar activity, no one questions the risk that someone
is incurring with that kind of decision. And yet that 2-hours to work and
2-hours back drive is, based on the stats that I've been able to find, around
1 micromort. Over the course of a year, that adds up to around 200 micromorts,
or roughly 1/5000 chance of dying. I can't find the data on cave diving, which
is no doubt higher than recreational diving, but SCUBA has a value of 5
micromorts per dive, so it's roughly equivalent to driving 1250 miles on a
highway. Someone doing 40 dives per year is taking on roughly the same risk as
that 50,000 mi/year driver.

Humans are really bad about estimating risk. We do it by equating risk to the
ease in which we can imagine something happening. It's why so many people are
afraid of statistically safe activities like air travel while underestimating
much more serious dangers. We need a framework, like micromorts, for thinking
about risk logically to better determine what amount of risk to take on and
then "spend" that risk budget in whatever way helps us get the most out of
life. Parents can say, "I'd like a 90% chance of being alive when my kids turn
10, a 75% chance of being alive when they turn 18 and a 50% chance of being
alive when they turn 30." Once you've decided on a risk threshold, you can
work backwards to determine how many micromorts you're allowed to take on each
year.

Otherwise, you're just living your life based on irrational fears.

~~~
jamra
This reads like the most sophistic argument to the point he was trying to
make. The diver was a cave diver, not a regular scuba diver. It's very
different and notoriously risky. He almost died in the same cave previously.
His point was well taken.

It doesn't mean that being risk averse is the _right_ way to live. It's a fair
point and a good thing to consider when you are a parent. That's all.

~~~
BearGoesChirp
>He almost died in the same cave previously.

While I get the emotional impact of this, it really shouldn't be an argument
either way once you begin using some framework to judge decisions.

Think of it this way, if I nearly died in a car wreck on the way to work,
would it be fine for me to never get in a car again? I almost died doing that
once!

It would make more sense to determine the risk. That he already nearly died
doesn't really change the risk profile. Cave diving is extremely risky. That
should be the important factor. Having nearly died should not.

------
acdanger
See also this story if you want to make sure you don't really want to go
diving in a subterranean cave:
[http://www.bbc.com/news/magazine-36097300](http://www.bbc.com/news/magazine-36097300)

------
belovedeagle
I wonder - did they take steps to replenish the cave's oxygen? If not, it's
useless for the next person...

I guess this is kind of silly and naive, but it's what I would do.

~~~
pavel_lishin
I'm a little surprised there aren't caches of emergency supplies for
situations like these.

~~~
manarth
Cave-divers are expected (and taught) to carry reserve gas supplies with them.
From the description, they had reserve supplies - enough reserves to search
for an hour - but failed to recover their guideline within that time.

The issue was that they lost their guide-line leading to the exit, rather than
running out of gas. In such a scenario, no amount of reserve caches could
really solve that problem.

------
A_Person
I'd like to address the false assumption in this thread that cave diving is
more dangerous than driving a car!

I cave dive on a regular basis with two other guys. We've dived together as a
team for nearly 10 years. I'm late 60s and single, the second guy is 50s and
has a partner but no children, and the third is early 40s with a six-year-old,
who he has every intention of seeing grow-up into adulthood.

We often dive in a system comprising a complex maze of 8kms of underwater
tunnels. Some are large, and would fit several divers across, but some are
small, and you can barely squeeze through. The only entry to and exit from
this system is a small pond, about 6 feet across and 4 feet deep, just big
enough for one person to get in at a time. Then you scrunch yourself up, and
drop down through a slot to enter the system.

We'd generally go about 700m into this system, making up to 13 seperate
navigational decisions (left? right? straight ahead?) which we have to reverse
precisely to get back out at the end. This is all completely underwater,
there's no air anywhere except for two air pockets hundreds of meters apart.
As I like to say, in cave diving there is no UP – there is only OUT!

It all sounds pretty dangerous, right? Wrong.

NAVIGATION. The whole system is set up with fixed lines, each of which has a
numbered marker every 50m or so. Before each dive, we consult the map, and
plan exactly where we're going to go. I commit that plan to memory, write it
down on a wrist slate, and also in a notebook which I take underwater. All
three of us do this independently. Underwater, when we come to a junction,
each of us checks the direction to go, then marks the exit direction with a
personal marker. If anyone makes a mistake, for example, turns in the wrong
direction, or forgets to leave a personal marker, the other two pick that up
immediately. On the way back, when we get to each junction, each of us checks
that it's the junction we expected, and we can see our personal markers. Each
individual's markers can be distinguished by feel alone, so we could get the
whole way back, separately, in total darkness, if we had to. So the odds of us
getting lost in the system are very low.

LIGHT. These caves are absolutely pitch black, so naturally you need a torch.
In fact, nine torches! Each of us individually has a multi-thousand-lumen
canister battery light, plus 2 backup torches, each of which would last the
whole dive. I could also navigate by the light of my dive computer screen, and
I'm considering carrying a cyalume chemical lightstick as well. So then I
personally would have five different sources of light, and we'd need 11
sources of light to fail before the team would be left in the dark. The risk
of this happening is basically zero.

GAS. Each of us has two tanks in a fully redundant setup. If one side fails,
we just go to the other and call the dive. In fact, our gas planning allows
one diver's entire gas supply to fail, at the point of maximum penetration,
and either one of the other two divers could get that guy back, plus himself,
without relying on the third diver at all. However, gas is certainly a limited
resource underwater, so it's always on our minds, and all three of us will
turn the dive as soon as anyone hits their safety limit.

There's lots more equipment involved, but let's leave it there for the moment,
and turn our attention to...

DRIVING! Each of us lives >400 km away from that system. So there and back is
a five hour drive. During that drive, you could fall asleep and run off the
road; have local fauna run out in front of your car; get head-on crashed by
drunken drivers, and so on. Several of those are external risks that are not
under our control.

So the simple fact of the matter is this. Our cave dives are almost certainly
SIGNIFICANTLY SAFER than driving to and from the dive site! The cave dives
carry significant potential risks, but most of those are mitigated with proper
training and equipment. Whereas there's not much I can do to stop a drunken
driver running head-on into me.

Certainly there are risks like tunnels collapsing and blocking the exit. But
statistically, I'm sure that those are orders of magnitude less likely than
having a heart attack, or falling over and breaking your neck.

Hope that helps :-)

~~~
cbr
[https://en.wikipedia.org/wiki/Micromort](https://en.wikipedia.org/wiki/Micromort)
has a single scuba dive as having the same risk of death as ~1700 miles in a
car. And cave diving is even more dangerous.

~~~
iaw
More interestingly, running a marathon is equally fatal as scuba diving.

Unfortunately I think the scuba-diving in this list includes _every_ type of
scuba and not the riskier types focused on in the articles linked in this
thread.

------
agentgt
_" I only turned it on when I went to pee or to climb down to get fresh
water," he says._

I know this is really dumb question but why did he need to turn on his light
to pee?

I presume he is in his wet suite?

~~~
x2398dh1
I would presume that he didn't want to pee in his water supply, perhaps? So he
had to aim very precisely toward a low-lying area.

------
ajarmst
Reminded me of the very sad story of Peter Verhulsel:
[http://www.upi.com/Archives/1984/11/12/Scuba-diver-lost-
in-c...](http://www.upi.com/Archives/1984/11/12/Scuba-diver-lost-in-cave-dies-
waiting-for-rescue/7366469083600/)

~~~
ajarmst
I'm a qualified advanced recreational diver, and most diving by properly-
trained (not 'quick tutorial at the dock' like a lot of tourists get) divers
has a very manageable level of risk, even at altitude or under ice. Cave
diving and mixture diving (esp. in overhead environments like the Andrea
Doria) is well beyond my personal acceptable-risk horizon, but most of the
people who go there are extremely experienced, well-equipped and cogniscant of
the risks and how to mitigate them. (Those that aren't tend to die or learn
they really shouldn't be there very fast). I would never call it safe, but
thise that go there (or, say, K2) aren't being foolhardy.

~~~
stordoff
What level of tuition should tourist divers be getting? I've only been diving
a few times, and we were given (what felt like) a reasonable amount of safety
briefings before even travelling to the dive site. IIRC the deepest we went
was 12-13m (third dive with the same crew; first two were sub-10m), and I was
under the impression (thought I'm __far__ from being an expert!) that it was
difficult to cause any major problems at those depths unless you do it all the
way the wrong way (i.e. fast/direct ascent to surface).

~~~
ajarmst
From 12m, all you'd need to do is hold your breath and surface rapidly to give
yourself a potentially fatal lung injury. Note that this is exactly what you
would reflexively want to do in nearly any emergency or if you just got
claustrophobic in the mask and reg (common) or had a sudden abyss panic (not
uncommon) or even a trivial even like having your mask kicked off by a buddy.
Recreational training should include a half dozen or so pool dives to practice
skills. This gives you the training and confidence to cleanly handle minor
emergencies, followed by three or four supervised training dives to test those
skills in a real environment, and to give you a comfort level that gelps
prevent panicy action later. Those first few dives to shallow depth are
actually among the most dangerous you ever do, because you're a novice in an
environment where your reflexes will kill you.

------
surgeryres
No one has mentioned the risk subjected upon the rescue team to come get him.
So there's that.

~~~
benzofuran
Rescue teams for caves are usually regional volunteer groups - and usually
it's body recovery. They go into it knowing what they're likely to find - very
rarely (if ever) are they first responders or typical public service
employees, at least as part of their job function

------
tysonrdm
There should be a law against bringing in and leaving nylon ropes in the cave.
If this continues, all the caves are going to be filled with nylons ropes left
by previous divers. Do we want these caves, too, to eventually become a
garbage dumping ground?

~~~
castis
"I'm not a cave diver, have no emotional attachment to this article, and I
don't have even a rudimentary understanding of the culture surrounding cave
diving but I made an account just to say I think those people should have
arbitrary limits placed on them."

~~~
Chris2048
With you, except for "no emotional attachment to this article" \- why is this
needed?

~~~
castis
They don't mention anything about the central topic of the article; the man
who was stuck in the cave. If they had any sort of emotional reaction to the
article, I imagine they would have said something about it.

~~~
Chris2048
I understand. My point is, why do they need an emotional reaction?

~~~
castis
They don't, no one does, but any one of the three things I listed would have
most likely caused someone to contribute something useful to the conversation.

