Swim throughs - what could possibly go wrong?

[ComputerX]

Assuming:

• There is only one clear path and no chance of getting lost;
• The floor is course sand that won't silt even with a group of divers swimming through the cavern;
• It is so spacious that many divers can pass through at the same time;
• The cavern has multiple large entries and exits; and
• It is well illuminated.

What are the risks of diving in these "caverns"? What could go wrong?

I hope I am not breaking some unwritten scubaboard protocol here, but I will try to answer the poster's question. I'm taking the assumptions as facts.

This is based on things that have actually happened to my girlfriend, who is a much more experienced diver than I am. Two while I was there, and one before I met her.

Before I met her she was swimming through a lava tube that required the divers to go single file. She hit the top of her tank on the overhead and knocked the valve loose. She says she still had air, but she had to swim quite a distance with bubbles everywhere before it could be fixed. She describes breathing getting difficult so she might have just been breathing the air out of the hose. It was fixed underwater and the dive continued. A DIN valve might mitigate the risk. Diving sidemount might help. I think the correct answer is to make sure you have redundant gas for your entire dive, not just portions of it.

In November we dove a cenote. She was hesitant, but the guide assured us it was always wide open and there was no reason to be worried. She told about the previous story and explained that she really didn't like enclosed spaces. She got talked into the dive. We got to an area that was wide but only about five feet from floor to ceiling. She got very buoyant and was pinned to the ceiling. The guide and I were able to keep her down long enough to swim her out of the area. The correct answer is to not let yourself get talked into a dive, but that is really hard to do. Neither of us knew what the inside of the cave looked at. From the descriptions and pictures I thought it would be fine. If I had known what we were in for I would have tried to keep her out. The guide tried to talk her into the second dive also. She wavered, but with a lot of pressure from me, she sat that one out. I think it was a good thing. I love the caverns and I want to progress to caves some day. She likes warm, shallow tropical water. Obviously the guide should not pressure divers. Being a little overweight might be a good idea. If a diver gets nervous and won't breathe all the way out they can have a hard time sinking. a little extra weight will get them down.

Over Christmas we were in Kona. One dive took us into a tiny cavelet (more like a hollow in the rock) and out a "lava tube" that was really a hole. It was, maybe, eighteen inches long. As she was going out, the surge grabbed her and gave her a good spin. That wasn't a big deal. But surge is an issue going through confined areas. Be aware of it. Have three or more professionals. One to lead, one at the tail, and one at the narrow spot to give assurance. And have a plan for what to do if you get half the group through then decide the surge is too strong for the rest of the group.

A common thread here is that the divers didn't know what they were getting into before the dive. Even with my few dives, I have been in that situation. A dive leader takes off into what looks like the mouth of a cave, and I have to decide if I am going to follow, or if I am going to risk getting separated from the group.

 

[Jax]

What do you guys who stick to the no overhead ever theory do in places like Cozumel where almost every dive has a swim thru? Do you leave the group and go above? Do you tell the dive guides that is inappropriate and unsafe to take rec divers thru these? Just curious?

#2 first -- Not my place to lecture to dive guides. I do tell the guide I am solo trained, don't do overheads in singles, and will be following the bubbles from on top of the coral.

#1 - Yes, I stick to the overhead guidelines when in Coz, diving a single, not having the proper equipment. I note where the group goes in, and remain above them, and follow bubbles.

 

[CamG]

IF not properly trained for overheads, or geared up appropriately it is easy to roll by the numbers, "FOLLOW THE RULES".
If you choose differently please think of others like RJP that have to go into these environments to retrieve you.
I used to use personally my comfort level with even Tech dives and if something was not quite right I would temper the dive plan accordingly.
Some days even when trained for overheads you do not feel it, DONT DO IT!
The cave, swim through, wreck, what ever will be there another, why push it?

Just my random thoughts,

CamG

 

[TMHeimer]

I've never gone into any overhead environment. Am no expert except what PADI tells me--don't go in there. 20m=60 feet. That would seem a long way. Is the exit visible from the entrance? I would probably go through something that's like 10' long, plenty wide, no entanglement possibility and you could easily see each opening. Can't imagine where I'd be to find such a place.

 

[Belmont]

You're between two people and the guy in front gets his mask and/or reg kicked out, now he's flailing and kicking and trying to turn around, silting up everything and causing panic up and down the line.

You're going through with your cute little single and bumping the ceiling and break an LP hose.

There is no such thing as a place that cannot be silted up . . .

You head in the 'tunnel' and come face to face with a Morey that is used to being fed by divers (he approaches you for a bite). Youout don't know how to back up, but you try, thus kicking the reg out of the guy behind you, who panics and comes for yours, forgetting about that octo thing, and you don't know where your octo is because the guy is all over you and the moray is wanting his bite. . .

Moron ahead of you doesn't know how to kick, so he smacks the coral just right and a cave-in occurs, leaving everything dark and feeling like a trap.

You're going through a swim-through and said cave-in happens, so you head down another tunnel, but this one dead-ends in a skinny area, and as you are pushing yourself backwards to get out, you roll off your valve and are OOA . . .

That enough?

---------- Post added February 2nd, 2014 at 09:44 AM ----------

.
.
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Oh, yeah . . . how to mitigate . . . :whatever:

Get the proper equipment, training, and experience to dive overhead safely.

Like the song says: When the sh... hits the fan...that's a moray.[video=youtube;Zi8beYR1iBQ]http://www.youtube.com/watch?v=Zi8beYR1iBQ[/video]

 

[Foxfish]

Interesting discussion to date. Some of you are getting hung up on the training aspect. I never said to assume that the diver did or didn't have training. If it makes you more comfortable, assume they have training.

Some of you would never enter an overhead environment as required by the limitations of your training. Fine. Do you understand the reason for the limitation? Maybe by reading a thread such as this you will become more aware of the risks involved. Having an understanding of the risks means you would be less likely to put yourself in a difficult situation in the future. Also keep in mind that knowing a whole bunch of facts about diving doesn't make you a good diver. One of the benefits of doing a course is that you can get feedback from a dive instructor on whether they think you are ready to progress beyond the limitations of your current certification.

For those who have what you consider to be the required training, what is the problem with sharing your experience and learning on the matter? I for one have found some of the scenarios described in this thread already interesting. I take everything I read on this board with a pinch of salt - sometimes a truckload. I'd want it backed up by a reliable source such as course training. However, the information provided can get a diver thinking and give you ideas that you can consider and check further. I think many of us have experienced that benefit from participating on the board. Further, I've found there are some aspects of diving that I have learned about on Scubaboard were not mentioned or only touched upon by my training course.

I don't believe that there is any Scubaboard requirement that prohibits anyone being involved with this discussion as outlined in the OP. This is an advanced forum and I'd expect that some who participate would have relevant specialty training.

Scubaboard will not allow discussion that promotes diving beyond a persons certification level. I think we can still have this discussion without doing contravening that requirement. Moderators, please feel free to correct me on this matter if I'm wrong.

I listed several assumptions for the dive just because they're the obvious ones and to help the discussion expand beyond 'it's dangerous, don't do it'. When I say a swim through or cavern is 20 m long it could have multiple exits allowing direct access to the surface along the way. If you think that a 20 m swim through is too long - why? How would you mitigate the risk? If swimming through a 20 m cavern with a single entry and exit is considered outside the realm of this forum, then what would you limit the length to and why? 1 m, 2m, 5m or 10m. How did you establish your criteria?

---------- Post added February 2nd, 2014 at 07:59 PM ----------

Panic is one concern. Example would be someone afraid of snakes seeing a sharp-tail eel and mistaking it for one, or freaking out when approached by the large green moray in Jax's example. The issue is, diver panics, attempts to bolt for the surface (bad in its own right), and hits the ceiling, then really panics, and so on.

Issue here is the mentality of the individual diver. For some that scenario would seem exaggerated and silly; for some it could be lethal. Seems like a few years ago I saw a thread where a diver was found dead 'stuck to the ceiling' of a cavern that's supposed to be easy. And drowned divers' bodies found without the weights ditched are another example of how panic makes situations dangerous that ought not to be.

If you swim too near the ceiling, even if space doesn't demand it, your tank valve can snag on something. That could freak someone out.

Also in another thread, someone posted about a wreck penetration (the Oriskany, I believe it was), and diver exhalation bubbles dislodging an overhead bristleworm (which I don't think stung anybody, but obviously it could've). My point it, people with no overhead training might not consider their bubbles might stir something up.

And as others have alluded to, many swim throughs are down by vacation divers new to the local site, on a 'trust me' basis, and it's up to you whether to do that. I've done swim throughs, and I've not done them. I'm chubby and in gear my girth is greater than the average diver, so swimming through tunnels concerns me.

Got this recurrent fear of being half-way through a fairly tight swim through and a big green moray popping out in close quarters (and yes, I wear split fins and don't know the back kick...).

Richard.

I think the unspoken assumption here and expressed by a number of others in this thread is that if you do the necessary certification somehow that is your magic pill to safe diving in an overhead environment. I spoke to one instructor recently regarding overhead diving courses. They do them in a dam and see it more as a lead up to cave diving than for use in the ocean. Clearly that is not going to teach you how to dive in an overhead environment, nor deal with surge or entanglement or scary eels. Oh and for the record I like eels.

I'm not saying you shouldn't do the training, but be aware that circumstances will change depending on where you dive and you should understand your training won't identify all the risks involved.

If nothing else, this thread is a chance to identify some that you may not experience in your area.

 

[drrich2]

I think the unspoken assumption here and expressed by a number of others in this thread is that if you do the necessary certification somehow that is your magic pill to safe diving in an overhead environment.

As a follow up, I've seen postings where people have derided some mainstream Wreck Diver specialty courses as inadequate preparation for penetration diving in wrecks, so indeed, certification doesn't always = competence.

Richard.

 

[tursiops]

Nothing is a "magic pill to safe diving." It is highly unlikely, however, that training will hurt.

The comment on recreational Wreck Diving doesn't train you for penetration is kind of missing the point....it is not a penetration course, it is about diving near and on wreck's not in them. That requires at least the Advanced Wreck course, and even that is just the beginning.

 

[Foxfish]

You seem to love " what the book says" Here is a refresher:

1.If a direct immediate ascent to the surface is not possible, rec, solo divers should not go there.

2. If you are a tech trained, wreck solo diver, we gave you enough training and info to make your own decisions and do not need to post add nauseam on the net to obtain validation of reckless behaviour.

Eric

It would be more correct to say that I have a healthy respect for what the major sports agencies teach and the recommendations and directives given in their course books. I'd encourage others to do the same.

It is becoming evident to me that as diving becomes more advanced (risky), opinion about the risks involved varies, even between agencies. That being the case, it is up to the diver to understand the risks and make sensible choices.

I believe one reason for this variance is the different environments in which we dive. There are some aspects of diving taught on courses that I consider to be impractical or irrelevant in our context. No one I've ever met follows the course recommendations on those aspects. That doesn't mean it is not useful and even important in some contexts. It doesn't necessarily mean it is not correct in our context. I have to make a choice.

Before contravening anything taught on a course, I like to have a good understanding of what the course intended to say, it's rationale and the risks involved.

---------- Post added February 2nd, 2014 at 09:16 PM ----------

In November we dove a cenote. She was hesitant, but the guide assured us it was always wide open and there was no reason to be worried. She told about the previous story and explained that she really didn't like enclosed spaces. She got talked into the dive. We got to an area that was wide but only about five feet from floor to ceiling. She got very buoyant and was pinned to the ceiling. The guide and I were able to keep her down long enough to swim her out of the area. The correct answer is to not let yourself get talked into a dive, but that is really hard to do. Neither of us knew what the inside of the cave looked at. From the descriptions and pictures I thought it would be fine. If I had known what we were in for I would have tried to keep her out. The guide tried to talk her into the second dive also. She wavered, but with a lot of pressure from me, she sat that one out. I think it was a good thing. I love the caverns and I want to progress to caves some day. She likes warm, shallow tropical water. Obviously the guide should not pressure divers. Being a little overweight might be a good idea. If a diver gets nervous and won't breathe all the way out they can have a hard time sinking. a little extra weight will get them down.

Over Christmas we were in Kona. One dive took us into a tiny cavelet (more like a hollow in the rock) and out a "lava tube" that was really a hole. It was, maybe, eighteen inches long. As she was going out, the surge grabbed her and gave her a good spin. That wasn't a big deal. But surge is an issue going through confined areas. Be aware of it. Have three or more professionals. One to lead, one at the tail, and one at the narrow spot to give assurance. And have a plan for what to do if you get half the group through then decide the surge is too strong for the rest of the group.

The ability and temperament of a diver has a big impact on the safety of diving in an overhead environment. What hardly registers with one diver can send another into a mad spin.

 

[Foxfish]

You head in the 'tunnel' and come face to face with a Morey that is used to being fed by divers (he approaches you for a bite). Youout don't know how to back up, but you try, thus kicking the reg out of the guy behind you, who panics and comes for yours, forgetting about that octo thing, and you don't know where your octo is because the guy is all over you and the moray is wanting his bite. . .

Firstly, don't feed the animals. The same thing could happen to an open water diver with the same result. I didn't learn anything on my open water course that would prepare me for that scenario.



We do encounter sharks in some of our caves that could give people a fright and even a bite if they were not careful. I'd avoid crowding into the cave to see the animal. If it bothered you, the risk could be mitigated by being aware of potentially dangerous animals in an area, keeping a healthy distance between you and other divers and ensuring that you are never far from an exit.

Moron ahead of you doesn't know how to kick, so he smacks the coral just right and a cave-in occurs, leaving everything dark and feeling like a trap.

You're going through a swim-through and said cave-in happens, so you head down another tunnel, but this one dead-ends in a skinny area, and as you are pushing yourself backwards to get out, you roll off your valve and are OOA . How to mitigate? Get the proper equipment, training, and experience to dive overhead safely.

What course and specific training did you do that would help you mitigate those risks?