r/CaveDiving

Why don't they massively overprepare? Like, what prevents them from taking 3 backpacks worth of stuff with them so that they'll get out of 95% of these dangrous situations that end up on social media easily, AND going there in a group of 3 at least. Of course that's slower but if dying isn't the core part of this activity I can't seriously consider this downside. In many news reports or social media videos people are literally diving absurdly dangerous caves with like a t-shirt and one light source (optional).

I've seen so many documentaries about various cave diving incidents and the horrific way those people died. Squeezing into spots so narrow you have to exhale to fit through, swimming in pitch black waters with nothing to guide you but a flashlight, the risk of nitrogen narcosis, knowing that even the most experienced cave divers have died because they got turned around. What makes that worth it? What makes you love it?

Super excited after doing some side mount diving in the caverns in Tulum last summer I’ve finally booked my Intro to Cave. Super excited to start this step! Didn’t really have anyone who “gets” it so figured I’d post here. Any advice I’d be happy to read but just wanted to share my excitement.

I had the pleasure of sitting down with Jill recently for a long conversation. I knew her reputation going in but nothing quite prepared me for how direct she was about the reality of what she does.

The death rehearsal protocol stopped me. Before every dive she sits at the surface and works through every possible way she could die that day. Methodically. Calmly. She doesn’t see it as morbid. She sees it as the only honest way to enter the water.

She’s lost more than 100 friends to cave diving. She talked about that too, what it costs, what it teaches, and why she’s still in the water.

The iceberg dive in Antarctica. Swimming three kilometres inside the Earth with no way to surface.

The moment she knew the Toronto ad agency life was over when she hid from her own client at the airport.

This is the most honest conversation I’ve had about what this world actually demands of the people in it.

Full conversation: https://youtu.be/XDO\_x5VSm8o?si=vMANvE3rXJIJr\_4Z

Wanna argue about CCRs? Cool! I post this here, in the Cave Reddit because it’s a somewhat cave-specific answer to a few CCR questions.

As a full-time instructor the answer I just wrote to one email covers a couple idea I seem to keep discussing with folks time and again. These are, for our area, in any case, the two most popular current configurations of CCR, and for good reason.

A few caveats to this response: I was asked about a few specific models, so the answer addresses those and it disregards backmounted models entirely. Not because they should be discounted, just because it wasn’t part of the question.

Also, I have no professional relationship with any of the mentioned manufacturers and am not endorsing or mudslinging any of them, simply acknowledging their existence and that they all have pros and cons.

For those of you who are going to tell me I’m an idiot for holding these opinions: I already know that.

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“Rebreathers. Yeah, EVERYONE has got opinions. And usually that opinion is, “Mine is the best there is and you should get one, too, and all other rebreathers are dumb.” I think people have to say that to justify the expense to themselves.

I’ve got a LOT of thoughts. Many of them seemingly contradictory. Mostly because, as you’re certain to find shortly, there isn’t really a “perfect” rebreather; they all have their benefits and drawbacks. A lot of it comes from the type of diving you’ll be doing and, possibly even more, personal preference. Definitely try a few and start getting a feeling for them, but I am sorry to say that it’s going to be very, very hard to know what you like and what you don’t until after you’ve been diving on the bloody thing for a few months.

My very first thoughts that are worth mention is that I’m not wild about chest-mounted units such as the Triton or the Symbios.

Two main reasons are Work of Breathing and dive profile.

WOB……. Think about pressure deltas, the difference in pressure in the water column; obviously the deeper you go, the higher the pressure. The delta between the counter-lung and your actual lungs being one of the key components that affects WOB on a CCR. With chest-mounted units, the counterlung is at least 15-20cm deeper than your actual lungs, which doesn’t sound like a lot. But it’s enough that your diaphragm, which usually relaxes as you exhale, actually has to work a little bit to inflate the counterlungs like blowing up a very easy balloon. But blowing up a balloon on every single breath for potentially hours. Will you notice it? Probably not. But your body will.

Then there’s the profile. Instead of a slipstreamed SM profile you have this thing on your belly. Might as well dive backmount for as much as it increases your profile. And I see a LOT of Choptima, Triton, and Symbios-shaped gouges in the silt.

All that needs to be read with a bit of a grain of salt, considering my prejudice against them. There are loads of people who love them and hundreds of safe dives made on them every day. The Symbios especially has a bunch of recent fans, and for good enough reasons as it’s got a couple of really cool features. And as far as packing….. yeah, they’re little and pretty flexible in terms of configuration (can be used with SM, BM, or even a single). Hell, if you were in the Carribean you could clip it to your belly, sling a AL40, and call it a day. Which is neat.

A long answer to a fairly simple question, huh?

Now on to the next one. Which is, I’m afraid, an equally long answer. mCCR vs eCCR

This, too, depends on where you’re looking to dive. And the short version is:
Here: manual without question
Pretty nearly anywhere else: either
Reason being depth changes.

On an eCCR you’ve got the electronics and the solenoid trying to maintain a set PPO2 at all times. Which is amazing when you’re bobbing around at 60 plus meters; any depth changes doesn’t really affect the PO2 too much because the ambient pressure difference between 60m and 55m is almost negligable. So if you ascend a little bit the solenoid doesn’t have much, if any, work to do.

The ambient pressure difference as you follow the contours of the caves here from 10m to 5m is HUGE. As you make that ascent a couple of things happen:
All the gas spaces on you expand quite a bit. Your drysuit, your wing, and your loop volume. The drysuit and the wing are easy enough to deal with. As, generally, is the loop volume. BUT, the solenoid starts to fire, too as the loop volume expands; because as it’s expanding, the PO2 is dropping, too. So now you’ve got this expanding loop, that is also getting filled with O2 which expands it more, that you need to vent to maintain buoyancy, which wastes O2. Now do that for a few hours. It’s a pain in the ass.

It’s a big enough pain in the ass that I pulled the solenoid out of my eCCR, turning it into an mCCR.

If I were diving elsewhere, I’d put the solenoid back in and let the electronics drive it. Especially if I had rapid descents to real depth, that’s where an eCCR really shines. This is, however, mostly because I’m lazy, not because I prefer or trust electronics.

On the whole, I tend to be more inclined towards manuals. They’re more flexible in my experience more reliable and predictable, and they’re just as easy to fly as an electronic. So lots of positives, with the only drawback being you have to pay a little more attention (but is that really even a drawback?)

More precisely, they’re not truly manual, but rather CMF CCRs. Constant Mass Flow, that have a “leaky valve” like the entire KISS line.

As to what I value most in a unit? Ease of diving and streamlined operation.

All that said, of the ones mentioned, if I were you and was going to buy one today? The Sidewinder. The original one. A used one for cheap as a first unit. In all honestly, I have been passively thinking about getting one of them myself for a while.

Not only is the Sidewinder 2 now out with some cool features, also worth consideration is the Fathom Gemini. Same ideas, some awesome philosophies built into it. Not superior/inferior, just different.

One nice thing about the configuration of what we can call Sidewinder-style CCRs…. The counterlungs wrap around your body at the exact same depth as your actual lungs. The WOB is almost exactly the same as you sitting there now, reading this in almost any body position in the water.

Another neat thing is that, if you ever have a problem with the rebreather on the surface, you unclip two bolt snaps, put the rebreather back in the bin, and then you go for a SM dive instead. The style does have its drawbacks, just like every configuration, but has some pretty big benefits.”

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Cutting off there as the rest of the email to our guest doesn’t concern you (you nosy bastards). And besides, I figure there’s already enough in there to get everyone worked into a lather about how I don’t know what I’m talking about.