Cenote diving as a recreational diver

[tursiops]

There's another rule, too, which is that you can't be more than 130 linear feet, depth and horizontal distance, from an exit.

The usual rule is "from the surface," not just "from an exit."

 

[halocline]

The usual rule is "from the surface," not just "from an exit."

In this case, they are one and the same, as cenote dives are in completely flooded caverns where there is often no access to the surface other than the exit. But you are correct, that 130 ft rule extends to the closest point at which surface air is accessible, not just the beginning of the line. Interestingly enough, I think this might be the rule that is stretched on some cavern lines. I frequently dive on the Tajma Ha cavern line because it leads to a couple of my favorite cave dives, the Chinese garden and the waterfall line. The cavern line is shaped like a big "U" and at the furthest point in, roughly halfway around the line, it's hard to me to imagine that a diver with a 130 ft of line in a spool could tie into the line and make it to an exit before running out of line. Somebody must have measured that at some point, as tour operators are busy every day with van loads of recreational divers doing this tour.

 

[DeepSeaExplorer]

@DeepSeaExplorer I don't recall a tail guide (although I was pretty focused on the dive/novelty). I thought Warren was at the end of our group, though.

I might be wrong about that. What do I know… I accidentally tipped the wrong guide after the dive.

 

[DeepSeaExplorer]

Well… we swam the line for 30 minutes and turned, resulting in a 60 minute dive. So we were a slow 30 minute swim from the surface at maximum penetration. The line had no distance markers, but it was certainly more than 130ft. So it exceeded the parameters of a cavern dive.

Now, at several points I could see light faintly in the distance. However, as I explained above, it’s too risky to go off line and try to make your own path to the surface, because the was no obvious path with all the formations and restrictions. (I don’t know if any cave agency that has going off line as an emergency procedure.) So, you have to reverse course and go back down the line you came in on, which is a 30 minute swim from the farthest point. That could probably cut that in half by swimming at cave speed. Had a diver chosen to go off line, he would probably be highly criticized for doing so.

 

[halocline]

Well… we swam the line for 30 minutes and turned, resulting in a 60 minute dive. So we were a slow 30 minute swim from the surface at maximum penetration. The line had no distance markers, but it was certainly more than 130ft. So it exceeded the parameters of a cavern dive.

Now, at several points I could see light faintly in the distance. However, as I explained above, it’s too risky to go off line and try to make your own path to the surface, because the was no obvious path with all the formations and restrictions. (I don’t know if any cave agency that has going off line as an emergency procedure.) So, you have to reverse course and go back down the line you came in on, which is a 30 minute swim from the farthest point. That could probably cut that in half by swimming at cave speed. Had a diver chosen to go off line, he would probably be highly criticized for doing so.

A couple of things, one is that 'restriction' is a defined term in cave diving that describes a spot in the route where it's tight enough so that only one diver can pass through it at a time. I am 100% certain that there are no actual restrictions on a cavern line. That would be unsafe and absolutely against all rules and norms. I'm not saying that there were no spots that felt 'restricted' but for sure they weren't so tight that 2 people sharing air couldn't make it through.

Second, I get what you're saying about the line length, as I mentioned it's like that on the Tajma Ha cavern line and probably several others. The mitigating factor is that there are supposed to be bail out options in which a guide could lead a distressed diver to the surface in 130 ft, or a diver could swim towards visible light and reach the surface in 130 ft. That's the way I believe the standards are. Is it in fact true that at any point during every cavern dive, a 130 ft clear path to a visible surface exists? I wouldn't put money on it either way. It's supposed to be from what I understand. For sure it's not like 300 ft.

As far as leaving the line, you are correct that in cave diving, if you leave the line in an emergency, like a search for a lost diver, you tie into the line with a safety spool, carrying the spool with you so that you have a continuous guideline back to the mainline and to the exit. In fact, a continuous guideline is one of the 'sacred' rules of cave diving; nobody violates that safely. But.......this is not cave diving. If you left the line on a cavern tour due to an emergency, presumably you would be swimming directly towards a visible exit. Not a great option, I agree. You have correctly identified one of the things about these cavern tours that make some people uncomfortable about their existence in the first place. You're not exactly in a cave, but you are also not in open water. The safety record over thousands of these tours has shown that they are about as safe as OW diving statistically. (I think, there's probably not the numbers to say that definitively) If I had to try to put some sort of WAG-type reasoning to it, I would say that the environment is absolutely riskier than just straight open water but the supervision, rules, and directions mitigate that risk.

Sorry about the long post, but you do bring up some interesting issues that we don't discuss carefully enough IMO.