Cavern with single tank?

[MrBigfins]

Well yeah, if you haven't even done one of those guided cenote cavern dives, then definitely start with that. It's what got me and many others hooked! Dos Ojos is a great one.

I disagree with this, I took cavern specifically to be able to safely do a guided cenote dive. Doing the guided cenote dive is a trust me dive, and sorry I don't trust anyone that much. That being said, what they consider cavern limits on the guided cenote tours FAR exceeds cavern limits. If truly adhering to cavern limits then I feel single tank is sufficient, but Mexico doesn't adhere to those limits in my experience. I would hope that during instruction for a certification, that standards are better adhered to than the trust me dives.

 

[Norwegian Cave Diver]

I disagree with this, I took cavern specifically to be able to safely do a guided cenote dive. Doing the guided cenote dive is a trust me dive, and sorry I don't trust anyone that much. That being said, what they consider cavern limits on the guided cenote tours FAR exceeds cavern limits. If truly adhering to cavern limits then I feel single tank is sufficient, but Mexico doesn't adhere to those limits in my experience. I would hope that during instruction for a certification, that standards are better adhered to than the trust me dives.

Perhaps a bit overstated. I suggested that if you were a AOW diver then the limit would be a combination of 100 feet. If a diver was 30 feet deep then there would be 70 feet to an exit. Is there areas that are more than 70 feet to an exit. Yes.

 

[fxb]

As a recreational diver, after having taken a cavern course, you will be limited to an absolute maximum of 130 feet to exit in PADI and I believe most other RSTC agencies, and 200 feet to exit in one of the other major ones I cannot recall (SDI? Anyone know?). AND to within the area of the cavern where there is still natural light. As Norwegian Cave Diver mentioned, the horizontal distance within the cavern to which you penetrate is added to depth.

That is the maximum recreational limit for penetration, both in cavern and wreck. Your depth is still limited to the scope covered by your experience and training. So as an AOW diver, at 100ft you could penetrate 30ft into a cavern. If you stay within these penetration limits, and factoring in your NDL, I can't imagine very many scenarios where a single cylinder wouldn't be sufficient.

So yes, it's definitely possible and in fact quite common to do cavern diving on a single tank!

On the other hand, even within recreational limits going sidemount (for example) can give you more bottom time in shallower caverns.

Here is the snippet taken directly from the 2019 PADI AOW Manual regarding a cavern adventure dive. This applies to the cavern specialties as well:

If entering a cavern, limit the dive to within the light zone and within 40 metres/130 feet from the surface, vertical and horizontal distance included.

 

[Scott]

I agree with tbone, you should have a conversation with Nat. Her and the team have upped the ante on training and even guided cenote dives for that matter. Not that Nat wants to weed people out but they don't want any part of the BS training that happens and knows that the difference between a cavern dive and cave dive is nothing. She may take an exception, but my hunch is not, based on conversations I've had with her.

 

[MrBigfins]

Perhaps a bit overstated. I suggested that if you were a AOW diver then the limit would be a combination of 100 feet. If a diver was 30 feet deep then there would be 70 feet to an exit. Is there areas that are more than 70 feet to an exit. Yes.

Take the Barbie line as an example, as a trust me dive you are at times 130 linear feet from an exit at 20' depth. The bigger issue is they won't review the map extensively, and you may be within 100-150' of an exit but it won't be the entrance you took and if you don't have a solid dive plan then you may not know which direction that exit is in. You are also far from the light zone in many locations and that is another requirement for staying within the cavern zone. So I don't really think it's an overstatement, and I wouldn't place my life in the hands of a guide without the proper training. Having that training helps you to better realize the dangers presented, how to handle them, and hopefully helps you to better discuss and plan the dive previously.

 

[Lorenzoid]

I disagree with this, I took cavern specifically to be able to safely do a guided cenote dive. Doing the guided cenote dive is a trust me dive, and sorry I don't trust anyone that much. That being said, what they consider cavern limits on the guided cenote tours FAR exceeds cavern limits. If truly adhering to cavern limits then I feel single tank is sufficient, but Mexico doesn't adhere to those limits in my experience. I would hope that during instruction for a certification, that standards are better adhered to than the trust me dives.

I admire your safety consciousness. The guided cenote “cavern” tours do push the boundaries of the training agencies’ definitions of “cavern” in a few places—that’s well known. And yes, they are the epitome of the dreaded “trust-me” dive. However, there are some other factors that might be considered. First, they have an excellent safety record. Guides with the reputable shops—hopefully essentially all of them these days—adhere to a code that, I believe, requires the guide to be in full cave diving gear, and provide a briefing on cave diving rudiments, among other things. Second, some of these dives follow routes that are punctuated by multiple ways to the surface, and you can often see some light from the surface even when it seems you are far into the dive. It’s definitely different than a cavern in Florida, where the agencies’ cavern training guidelines were developed. Still, I wouldn’t disagree with your instinct to get some more training than the average diver who goes on these dives, oblivious to what’s involved.

 

[MrBigfins]

I admire your safety consciousness. The guided cenote “cavern” tours do push the boundaries of the training agencies’ definitions of “cavern” in a few places—that’s well known. And yes, they are the epitome of the dreaded “trust-me” dive. However, there are some other factors that might be considered. First, they have an excellent safety record. Guides with the reputable shops—hopefully essentially all of them these days—adhere to a code that, I believe, requires the guide to be in full cave diving gear, and provide a briefing on cave diving rudiments, among other things. Second, some of these dives follow routes that are punctuated by multiple ways to the surface, and you can often see some light from the surface even when it seems you are far into the dive. It’s definitely different than a cavern in Florida, where the agencies’ cavern training guidelines were developed. Still, I wouldn’t disagree with your instinct to get some more training than the average diver who goes on these dives, oblivious to what’s involved.

You are correct, they do seem to have a solid safety record. However, personally I would prefer not to be the 1/1000 that it doesn't go well for. In my experience the 2 ops I have used did adhere to the standard of full cave gear with long hose and redundant air etc. There are multiple exits, the problem with that is on a guided cenote tour there is a cursory review of the map and dive plan. Someone who doesn't know better takes it at face value and will most likely not digest other potential exits. I wouldn't have placed as much emphasis on it prior to taking a cavern course. So when SHTF is the typical OW diver going to be able to assess location on the line and what the best exit is?

Sorry didn't mean to hijack the thread and turn it into a discussion of wether or not cavern DSDs are safe and appropriate. Return to your previously scheduled programming now

 

[tursiops]

I just returned from a week in Akumal (Villas De Rosa) with a small group of 3 cave divers, 5 OW divers, and 4 divers taking the cavern class. The instructor for the cavern class (which used the NSS-CDS Cavern Manual) was Alessandra Figari. She was excellent. None of the students indicated any interest in going on to cave, so the class was in recreational gear; it would have been nice if at least one of the students had had a 5 or 7 ft hose for the air-sharing exercises, but it was not mandatory. The class was originally planned for two days, but after the first day Alessandra said it would take three minimum, then a land-injury to one guy's leg slowed him down, so he took 6 days, another took five days, the other two finished in 4 days.
Watching her work, having her talk to me at the end of each day, and hearing from the students, I am greatly impressed. I wish my own cavern class had been nearly so good.
She is highly recommended.

 

[tursiops]

cavern DSD

There is no such thing. Using DSD -- which already has a defined meaning -- to denigrate the cavern dives you dislike, is demeaning to both DSDs and to the cavern dives.

 

[Esprise Me]

Not going to jump into the fray myself; I think both sides make good points. But I don't mind the discussion on the wisdom of guided cavern dives for OW divers. I think it's relevant to the general subject matter, plus it bumps the thread so more people see it and can give their input on my question.

I'm a little surprised there's so much support here for the idea of doing cavern in a single tank; I guess if I'd had to place a bet, I would've bet on this board leaning the other way. I'd be curious to hear more about people's reasons.