Are swim-throughs really caverns?

[shoredivr]

Reminds me of some of the lava tubes in Hawaii

 

[TSandM]

You know, I wondered about this when we did the Cathedrals off Lanai. We swam into a huge room, which was very well lit from multiple openings, but only had a couple of exits. I felt a twinge of guilt, because I was very well taught that OW divers did not belong in overhead environments, and that's clearly what I was in. However, you could not silt out the Cathedrals if you tried (I know, because some of my companions tried quite hard) and there is no navigation involved. The only way you could get into significant trouble would be to do something like run out of gas and panic inside the chamber, which I suppose could happen but obviously doesn't, or we'd read about it.

On the other hand, long single-file tubes at major depth, like Devil's Throat, sound scary to me, and I was quite happy that our group's use of Nitrox in Cozumel gave us a good reason not to do that dive (I don't think any of us would have done it anyway).

It isn't just getting lost. It's problem-solving underwater, or coping with a problem until you can get out of where you are and up to the surface. The training I've had (even before I took my cave course) has been focused on learning to manage as much as possible underwater if need be, but I don't think very many people do that kind of training. Still, it's obviously a testimonial to the reliability of equipment and how good guides are that we don't read about more issues with the longer and deeper "swim throughs".

 

[Alex777]

<< Have only glanced @ this thread but have 3 quick questions1) What is Bonnie's Arch dive(off Grand Cayman) considered (2) what is Devil's Throat dive(here I'm meaning when you enter @ 80' & come out @ 125') off Cozumel considered & (3) what is Eden's Rock/Devil's Grotto dive off Grand Cayman(@Georgetown) considered????.....TIA........ >>

Bonnie's Arch is not a swim-through or a cavern. It's just, well, an arch. Eden Rock & Devil's Grotto each have "swim-throughs" which fail some of Rick's criteria. Cruise ship divers are taken through the larger swim-throughs there every day.

 

[almitywife]

A swimthrough ....
Rick

WOW Rick....on little food and less than 4hrs sleep that attachment needs a kleenex warning!!!!!

i was led to this thread because my question elsewhere was very similar to OP's here.

on holidays i often find a guide will lead you to a wreck, you go wow and then are expected to blindly follow the guy in and dive it despite the fact the penetration was not mentioned during dive briefs.

in the past i have always refused to enter and then find myself outside the wreck, following escaping bubbles as they make their way thru

why do i refuse? because i dont have the basics, ie; a clue where we are going, a clue how to get out, no line, no wreck expereience and if i add narc'd to it - i just dont enter and after the dive when people say something, well they can kiss my :mooner:

thanks

 

[Ber Rabbit]

I found something fascinating in NAUI's open water standards manual, it said you cannot take OW students into overhead environments then it said "Except" and listed several exceptions including "swim throughs". I called to ask about it and was told you "can" take OW students into swim throughs but it's not recommended.
Ber :lilbunny:

 

[Dive-aholic]

This is done every day of the week & twice on Sundays in the Caribbean, how many accidents have you heard of??....so summizing, I would have to think it's very safe...

I realize it's done everyday several times a day. That doesn't make it safe. It just means they're lucky...or they're media doesn't report the injuries/deaths. I know of 2 deaths that happened at Ginnie Springs in the Ballroom - an overhead that is considered "safe" for OW divers.

 

[diver 85]

Thanks, everyone, for the replies.

<< A swimthrough is only a swimthrough (not an overhead) if it meets the following criterea (my definition):
(1) You can see the exit from the entrance, and for the entire swim through the swimthrough.
(2) You can see that there's plenty of room to make the swim without entanglement hazard and without any "squeezes" (restrictions).
(3) The total distance from the entrance to the surface is less than the distance you can perform a CESA; in no case more than 130'. >>

The swim-throughs I have in mind as examples easily fail this test. Trinity Caves (on Grand Cayman) and Mary's Place (on Roatan) don't even come close - they fail all 3 conditions. BTW, Mary's Place is THE signature dive on Roatan and most tourists on a dive vacation are taken through it.

For most plain-vanilla recreational divers, many of the swim-throughs on Grand Cayman's North Wall fail condition #3. The entrance is often at about 70 - 90 feet. In any event, once you are inside the swim-through you will ordinarily have divers ahead and behind you, and there is little room to get past them as you begin your CESA.

As for the IANTD definition, I think Trinity Caves qualifies as a cave and earns its name. There are points in the system where you are more than 120 linear feet from the surface by my estimation.

Mary's Place is just a long crack in the reef(see poor quality pic below) on the south side of Roatan......It was 'closed to the public' in the early to mid 90's & 'reopened' in '01 or '02 (if my memory serves me correct).You also had to view a video of it & be 'OK'ed' by the dive shop taking you there before going

(good dive skills etc...).....
)

 

[MauiScubaSteve]

From my NSS-CDS Cavern Diving Manual, cavern diving in standard recreational scuba gear follows these limits;

Direct Sunlight Zone - diver can see the opening (entrance/exit). If you can not see the opening but it is not pitch black, you are in the ambient-light zone. When it is pitch black and you can see nothing without lights you are in the zone of total darkness. Cavern diving is only in the direct-sunlight zone.

130' Maximum Linear Distance from the Surface - Cavern divers must stay within a linear distance of 130' to the surface. Linear distance includes the depth of the entrance plus the distance of penetration. Examples; 30' deep entrance plus 100' penetration, 50' deep entrance plus 80' penetration, 70' deep entrance plus 60' penetration.

70' Max Depth - Below 70' air reserves for dealing with emergencies are too limited and the margin for error becomes too critical.

No Restriction - Buddy teams should be able to comfortably swim side by side. If divers have to swim single file due to localized narrowing that is considered a restriction. Cavern divers are not permitted to pass through restrictions in part because sharing air with standard scuba through a restriction is nearly impossible.

40' Minimum Visibility - The minimum visibility acceptable for cavern diving is 40'.

No Decompression Limits - Cavern divers should stay well within the no-deco limits. When cavern diving, bottom time is the time from leaving the surface until returning from the cavern to a depth of 10' in open water(not ending at start of ascent). Most experienced cavern divers stay within 80% of NDL limits, to allow for any unexpected delays during exit.

Air Supply Limitations - One of the three leading causes of death in underwater caves is failure to reserve adequate air for exiting. This requires at least as much air in each cylinder as both divers (buddy team) used coming in on the two seperate cylinders (basic rule of thirds).

If you are in any of these following situations, you are technically in cave diving territory; ambient-light zone or zone of total darkness, more than 130' linear from surface, deeper than 70', past a restriction less than 2 divers wide, less than 40' visibility, more than 3 minite required saftey stop. Violating the rule of thirds does not put you in cave diving territory, you are just very foolish.

 

[BTravlin]

Mary's Place is a long swim through crack in the reef and is single file narrow almost all the way through. It is also open overhead almost all the way through as well. Depth was in the 80-90 fsw range if I remember correctly. Our DM took us through and we were on maybe dive # 10 after our OW.

 

[MauiScubaSteve]

The (IANTD) definition of a cavern dive is any dive in overhead with LESS than 120ft linear distance to the surface, MORE than that and it´s a cavedive. If you enter a swimthru at 100ft it can´t be more than 40ft long before it becomes a cavedive which is no place to be without the appropriate training and equipment.

Since IANTD basically adopted CDS limits when starting their Cavern Diver cert, I am relatively sure 130' is their linear limit also. Since the NSS-CDS Cavern Diving Manual is/was an approved text for IANTD Cavern Diver, I would be suprized if a 100' deep entrance is considered cavern by IANTD.